Regulation of the natural growth or development of plants with 2-sulfinyl or 2-sulfonyl pyridine N-oxide compounds

ABSTRACT

2-Thio, 2-sulfinyl and 2-sulfonyl pyridine N-oxides of the formula ##STR1## ARE USEFUL FOR REGULATING THE NATURAL GROWTH OR DEVELOPMENT OF PLANTS. E.g., the compound wherein n = 1, R 1  = methyl and R 2  = 2,3,4-trimethylphenyl retards cotton and increases root growth of turf.

This invention relates to a method of regulating the natural growth ordevelopment of plants using certain 2-substituted pyridine N-oxides,some of which are believed to be new compounds.

Certain of the compounds employed in the present invention are disclosedas herbicides in commonly assigned copending applications Ser. Nos.559,188 now U.S. Pat. No. 4,019,893 issued Apr. 26, 1977 and 559,196(now U.S. Pat. No. 3,960,542 issued June 1, 1976) of Howard L. Plant andAllyn R. Bell, filed Mar. 17, 1975. Other compounds employed herein aredisclosed as herbicides in U.S. Pat. Nos. 3,107,994, Rawling et al.,Oct. 22, 1963 and 3,155,671, D'Amico, Nov. 3, 1964, or aspharmaceuticals in U.S. Pat. No. 3,772,307, Kaminsky et al., Nov. 13,1975. However, the non-herbicidal treatment of plants with the presentlyemployed compounds has not heretofore been disclosed, insofar as thepresent inventors are aware. Certain compounds, to be pointed outhereinbelow, are new chemicals.

In the light of present and future world food problems the necessity toincrease productivity in terms of plant efficiency is of paramountimportance. Chemical manipulation of plant metabolism to producedesirable results as needed is an effective answer to the situation.

The present invention surprisingly makes it possible to increase theefficiency of photosynthesis by reducing photorespiration. Improvementin yield of major crops such as soybeans, peanuts, cereal grains andcotton can therefore be achieved by more efficient conversion of CO₂into organic compounds by these plants. The method of the invention ingeneral involves regulating the natural growth or development of plants,by applying to said plants an effective plant-regulating amount of a2-thio-, 2-sulfinyl-, or 2-sulfonyl-pyridine N-oxide of the followingformula I: ##STR2## wherein: N IS 0, 1 OR 2;

R₁ is hydrogen, alkyl (C₁ to C₁₅), phenyl or benzyl;

R₂ is hydrogen, alkyl (C₁ to C₁₂), alkenyl (C₁ to C₄), alkoxycarbonyl(C₂ or C₃), alicyclic (C₅ to C₆), phenyl, phenyl substituted with from 1to 5 substituents which may be the same or different and are selectedfrom the group consisting of lower alkyl (C₁ to C₃), halogen, cyano,nitro, alkoxy (C₁ or C₂), phenoxy, dioxymethylene and2,2-dichlorocyclopropyl; 1-methyl-2,2-dichlorocyclopropyl,2,2-dichlorocyclopropyl, polycyclic (naphthyl, anthryl), biphenyl,heterocyclic or benzyl;

R₁ and R₂ may be joined together in the form of a polymethylene chain--(CH₂)_(m) -- where m is 3, 4 or 5 to form a carbocyclic ring;

and when R₁ is hydrogen or methyl R₂ can be the radical ##STR3##

where y is 0, 1 or 2 and the X's are the same or different and areselected from lower alkyl (C₁ to C₃), halogen, and2,2-dichlorocyclopropyl.

Certain highly desirable sulfides having the above structure arebelieved to be new chemical compounds, namely, those of the followingformula II: ##STR4## wherein R₁ is C₃ to C₁₅ alkyl; and

R₂ is 2-naphthyl, phenyl, or phenyl substituted with from 1 to 3substituents which may be the same or different selected from methyl,chlorine and phenoxy.

The new chemicals of formula II include compounds that are remarkable incertain aspects of their activity.

The compounds employed in this invention, as defined by the aboveformula, to influence the natural growth or development of plant lifehave been found to be surprisingly effective plant regulators. It is tobe understood that the term "plant regulator" is used herein in itscommon usage and means a substance which, through physiological action,will accelerate or retard the rate of growth or rate of maturation orotherwise alter the behavior of ornamental or crop plants or the productthereof. Thus, the usage herein conforms to the definitions provided byCongress in Public Law 92-516, the Federal Environmental PesticideControl Act of 1972, section 2, subsection v, wherein the term "plantregulator" is defined as any substance or mixture of substancesintended, through physiological action, for accelerating or retardingthe rate of growth or rate of maturation, or for otherwise altering thebehavior of plants or the produce thereof, but shall not includesubstances to the extent that they are intended as plant nutrients,trace elements, nutritional chemicals, plant inoculants, and soilamendments (see also U.S. Pat. No. 3,904,395, Eilrich et al., Sept. 9,1975).

Thus, in accordance with this invention a method is provided wherebyviable plants are treated with a chemical substance which alters theirnatural growth or development to enhance various agricultural orhorticultural features of the plants. As employed herein, the term"natural growth or development" designates the normal life cycle of theplant in accordance with its genetics and its environment, in theabsence of artificial, external influences.

The term "active ingredient" will be used hereinafter in thisspecification to connote one or more of the compounds of the aboveformula.

It is to be understood that the regulation of natural growth anddevelopment does not include killing or herbicidal action. Althoughphytotoxic or lethal amounts of the active ingredient might be employedto destroy certain plants, it is contemplated here to employ only suchamounts of said active ingredient as will serve to regulate the naturalgrowth and development of useful plants without substantial injury. Asmay be expected, and as long understood by those skilled in the art,such effective plant regulating amounts will vary, not only with theparticular active ingredient selected for treatment, but also with theregulatory effect to be achieved, the species of plant being treated andits stage of development, and whether a permanent of transientregulating effect is sought. Other factors which may bear upon thedetermination of an appropriate plant regulating amount include theplant growth medium, the manner in which the treatment is to be applied,weather conditions such as temperature or rainfall, and the like.

In accordance with the instant invention it has been found thatdesirable regulation of natural plant growth or development is achievedby application of the active ingredient to plants in various states ofdevelopment. It will be understood that such expressions as "applying toplants" as used herein include applying to plant parts (e.g., seeds) andextend to indirect application (i.e., applying to soil in which theplant is growing or is to be grown) as well as direct application. Thus,the compounds can advantageously be used as a seed treatment. They canbe applied to the soil, and seed or transplants planted in the treatedsoil, or applied to the plant in the seeding stage, flowering stage orfruiting stage and the like, or can be applied to plants at more thanone stage of development. Such application may be made directly to oneor more of the plant's parts, such as, stems, leaves, flowers, fruit orthe like.

Regulation of the natural growth or development of plants by chemicaltreatment results from the effect of the chemical substance on thephysiological processes of the plant and the effect of such substancemay be manifested by the morphology of the plant. As should be readilyapparent, said regulation may also result from a combined or sequentialeffect of the chemical manifesting a response in both physiology andmorphology.

In general, regulation of the natural growth or development which leadsto a morphological change in the plant is readily noticeable by visualobservation. Such changes can be found in the size, shape, color ortexture of the treated plant or any of its parts. Similarly, changes inthe quantity of plant fruit or flowers can be simply noted.

On the other hand, regulation which leads to changes only in thephysiological processes occur within the treated plant and are usuallyhidden from the eye of an observer. Changes of this type are most oftenin the production, location, storage or use of naturally occurringchemicals, including hormones, within the plant. Physiological changesin a plant often are recognized when followed by a subsequent change inmorphology. Additionally, there are numerous analytical procedures knownto those skilled in the art for determining the nature and magnitude ofchanges in the various physiological processes.

The individual compounds employed in the instant invention serve toregulate the natural growth or development of treated plants in a numberof diverse ways and it is to be understood that each compound may notproduce identical regulatory effects on each plant species or at everyrate of application. As stated above, responses will vary in accordancewith the compound, the rate, the plant, etc.

One regulatory response demonstrated by the compounds useful in thepractice of this invention can be generally termed retardation ofvegetative growth and such a response has a wide variety of beneficialfeatures. In certain plants this retardation of vegetative growth causesa diminution or elimination of apical dominance leading to a shortermain stem and increased lateral branching. This regulation of thenatural growth or development of plants produces smaller, bushier plantswhich often demonstrate increased resistance to climatic extremes, pestinfestations and the like. Thus, the method of this invention providesfor plants that are in a good state of health and tends to produce moreeffective plants.

The individual compounds employed in this invention regulate the naturalgrowth or development of treated monocotyledonous and dicotyledonousplants in numerous other and different respects. Included among theseother regulatory effects are inducing or preventing axillary buddevelopment. The compounds will also promote the abscission of leaves,flowers and fruits. On cotton such a process has the additional benefitof reducing the potential feeding sites of such important insects as theboll weevil and the pink bollworm by either terminating the growth ofthe plant or by abscissing young fruiting bodies which are a preferredsource of food for insects. Other effects include the alteration ofshape of canopy, the delay or acceleration of fruit or pod set, etc.Although regulatory effects such as those described above can bedesirable, often it is the ultimate result of these effects upon theeconomic factor which is of primary significance in crop plants or uponthe aesthetic factor in ornamental plants. Thus, it must be recognizedthat increases in yield of individual plants, increases in the yield perunit of cropping area, improvement in the quality of the plants'product, improvement in the plants' vigor and reductions in the cost ofharvesting and/or subsequent processing are all of an individualregulatory effect during the growth or development of a plant. Thus,these compounds promote maturity of some plants. This effect isdesirable since earlier harvest can be made. This is especiallyimportant for cotton in some areas of the United States and othercountries.

The practice of the method of this invention is particularly useful forimproving the efficiency of row crops such as soybean (Glycine). Theapplication of the 2-thio-, 2-sulfinyl- or 2-sulfonyl-pyridine N-oxidesof the above formula to such growing crop plants reduces the stature ofthe plants without the expected substantial reduction in seed yield. Inthis manner the plant's efficiency of production is improved and a meansis provided for optimizing the crop by increasing the plant populationper unit area and treating said crop with the active ingredient duringits growing stage. Such reduction in plant stature also increasesaccessibility to the field for other treatments, cultivation andharvesting.

The productivity of some plants can be increased by controllingphotorespiration. About 5 to 10% of the dry matter of plants comes fromthe minerals and nitrogen of the soil. The balance or 90 to 95% of thedry weight comes from the conversion of CO₂ from the atmosphere by thephotosynthetic process. Some plants are efficient converters of CO₂ todry matter, but many such as soybeans, cotton and the cereals areinefficient users of CO₂. These plants photorespire or release CO₂ underillumination during the daytime. If this loss of CO₂ during the daytimeis eliminated in soybeans, a theoretical yield increase of 50% ispredicted. The present invention makes it possible to reducephotorespiration with a corresponding increase in yield.

In selecting the appropriate non-herbicidal rate of application of theactive ingredient, it will be recognized that precise dosages will bedependent upon the plant species being treated, the development stage ofthe plant, the particular chemical employed, the mode of application(whether to seed, soil, or directly to the plant itself) and variousother factors known to those skilled in the art. In general, the activeingredients are applied to seed, soil or to plants at rates of fromabout 0.05 to about 10 or more pounds per acre. Foliar applications offrom 0.1 to 5 pounds of the active ingredient per acre are preferred.

Manifestations of regulant activity include dark foliar color resultingin a darker green plant indicating higher chlorophyll activity (improvedrate of photosynthesis), altered canopy, leaf inhibition or abscission,promotion or prevention of axillary bud development, increased pod set,increased tillering, height reduction, promotion of root growth,improved photosynthetic activity by reducing photorespiration.

By way of non-limiting example, Table I below sets forth a number ofplant regulant 2-thio-, 2-sulfinyl and 2-sulfonyl-pyridine N-oxides ofthe above formula I useful in the invention. Methods of preparing suchcompounds have been described in copending applications Ser. Nos.559,188 and 559,196 mentioned above (the disclosures of which are herebyincorporated herein by reference) and U.S. Pat. Nos. 3,107,994,3,155,671 and 3,772,307 mentioned above, as well as Katritsky andLagouski-Chemistry of Heterocyclic N-oxides, Academic Press (1971) (seealso U.S. Pat. Nos. 3,005,852, Freyermuth et al., Oct. 24, 1961,3,006,962, Schultz et al., Oct. 31, 1961 and 3,006,963, Buc et al., Oct.31, 1961). The sulfides (i.e., the 2-thiopyridine N-oxides) are commonlyprepared from 2-chloropyridine N-oxide with a suitable mercaptan andacid acceptor or conversely the sodium salt of 2-mercaptopyridineN-oxide with a suitable halide. The more biologically active sulfoxides(i.e., the 2-sulfinyl pyridine N-oxides) and sulfones (i.e., the2-sulfonyl pyridine N-oxides) are prepared in the manner described inthe aforementioned applications, Ser. Nos. 559,188 and 559,196. Ingeneral, the oxidation of the pyridine N-oxide sulfides to sulfoxidesand sulfones is accomplished by employing 30 to 50% hydrogen peroxide ina suitable solvent such as acetic acid or water. The peroxy acids suchas peracetic, perbenzoic and metachloroperoxybenzoic work well insolvents varying from chloroform and methylene chloride to glacialacetic acid. When hydrogen peroxide is the oxidant of choice then ametallic acid catalyst such as vanadium, tungsten or molybdenum may beused to advantage but is not essential. Certain sulfides of pyridine canbe oxidized directly to the pyridine N-oxide sulfone in a single step.The sulfoxides are not available by this technique. Table I gives thesystematic name, melting point (uncorrected, taken on an A. H. Thomasapparatus), empirical formula and analysis for a variety of exemplary2-thio-, 2-sulfinyl- and 2-sulfonyl pyridine N-oxides useful in theinvention; an X mark in the last column of Table I, headed "IR",indicates that the structure was confirmed by infrared spectrographicanalysis (using a Perkin Elmer Infracord [trademark]). The numbersassigned to the compounds in Table I are used to identify the compoundsin subsequent examples.

                                      TABLE I                                     __________________________________________________________________________                                                 Analysis                                                              Empirical                                                                             Calc/Found                       No.      Name                   m.p. Formula C   H   N   S   IR               __________________________________________________________________________    1   2-(2,2-dichlorocyclopropylmethylsulfinyl)pyridine                                                         Oil  C.sub.9 H.sub.9 Cl.sub.2 NO.sub.2                                                                     X                    N-oxide                                                                   2   2-(phenylmethylthio)pyridine N-oxide                                                                       164-166°                                                                   C.sub.12 H.sub.11 NOS   X                3   2-(2,2-dichloro-1-methylcyclopropylmethyl-                                                                93-95                                                                              C.sub.10 H.sub.9 Cl.sub.2 NO.sub.3                                                     ##STR5##                                                                          ##STR6##                                                                          ##STR7##                                                                          ##STR8##                                                                         X                    sulfonyl)pyridine N-oxide                                X                4   2-(phenylmethylsulfonyl)pyridine N-oxide                                                                  126-128                                                                            C.sub.12 H.sub.11 NO.sub.3 S                                                                          X                5   2-(1-naphthylmethylthiopyridine) N-oxide                                                                  130-133                                                                            C.sub.16 H.sub.13 NOS   X                6   2-(3,4-dimetylphenylmethylsulfonyl)pyridine                                   N-oxide                     165-167                                                                            C.sub.14 H.sub.15 NO.sub.3 S                                                           ##STR9##                                                                          ##STR10##                                                                         ##STR11##                                                                         ##STR12##                                                                        X                7   2-(4-methylphenylmethylsulfonyl)pyridine N-oxide                                                          149-151                                                                            C.sub.13 H.sub.13 NO.sub.3 S                                                                          X                8   2-(4-chlorophenylmethylsulfonyl)pyridine N-oxide                                                          154-155                                                                            C.sub.12 H.sub.11 ClNO.sub.3                                                                          X                9   2-(1-naphthylmethylsulfonyl)pyridine N-oxide                                                              183-186                                                                            C.sub.13 H.sub.16 NO.sub.3 S                                                                          X                10  2-(4-chlorophenylmethylthio)pyridine N-oxide                                                              121-123                                                                            C.sub.12 H.sub.10 ClNOS X                11  2-(4-methylphenylmethylthio)pyridine N-oxide                                                              121-124                                                                            C.sub.13 H.sub.13 NOS   X                12  2-(4-chlorophenylmethylsulfinyl)pyridine N-oxide                                                          104-107                                                                            C.sub.12 H.sub.10 ClNO.sub.2                                                                          X                13  2-(2,5-dimethylphenylmethylthio)pyridine N-oxide                                                          141-143                                                                            C.sub.14 H.sub.15 NOS   X                14  2-(2,5-dimethylphenylmethylsulfonyl)pyridine N-oxide                                                      156-158                                                                            C.sub.14 H.sub.15 NO.sub.3 S                                                           ##STR13##                                                                         ##STR14##                                                                         ##STR15##                                                                         ##STR16##                                                                        X                15  2-(4-nitrophenylmethylsulfonyl)pyridine N-oxide                                                           215- 216                                                                           C.sub.12 H.sub.10 N.sub.2 O.sub.5                                                                     X                16  2-(cyclohexylmethylsulfonyl)pyridine N-oxide                                                               144-145°                                                                   C.sub.12 H.sub.17 NO.sub.3 S                                                                          X                17  2-(2,2-dichlorocyclopropylmethylsulfonyl)pyridine                                                         103-105                                                                            C.sub.9 H.sub.9 Cl.sub.2 NO.sub.3                                                                     X                    N-oxide                                                                   18  2-(2-ethylphenylmethylthio)pyridine N-oxide                                                               114-118                                                                            C.sub.14 H.sub.15 NOS   X                19  2-(ethylsulfinyl)pyridine N-oxide                                                                         94-96                                                                              C.sub.7 H.sub.9 NO.sub.2 S                                                                            X                20  2-(2-benzothiazolylmethylsulfonyl)pyridine N-oxide                                                        175-176                                                                            C.sub.13 H.sub.10 N.sub.2 O.sub.3                                             S.sub.2                 X                21  2-(2-methylphenylmethylthio)pyridine N-oxide                                                              134-136                                                                            C.sub.13 H.sub.13 NOS   X                22  2-(2-chlorophenylmethylsulfonyl)pyridine N-xodie                                                          151-152                                                                            C.sub.12 H.sub.10 ClNO.sub.3                                                                          X                23  2-(2-chlorophenylmethylthio)pyridine N-oxide                                                              111-113                                                                            C.sub.12 H.sub.10 ClNOS X                24  2-(dodecylsulfonyl)pyridine N-oxide                                                                       49-51                                                                              C.sub.17 H.sub.29 NO.sub.3 S                                                                          X                25  2-(dodecylthio)pyridine Noxide                                                                            87-89                                                                              C.sub.17 H.sub.29 NOS   X                26  2-(1-phenylethylthio)pyridine N-oxide                                                                     112-114                                                                            C.sub.13 H.sub.13 NOS   X                27  2-(2-methylphenylmethylsulfonyl)pyridine N-oxide                                                          159-161                                                                            C.sub.13 H.sub.13 NO.sub.3 S                                                           ##STR17##                                                                         ##STR18##                                                                         ##STR19##                                                                            X                28  2-(x,y-dichlorophenylmethylsulfonyl)pyridine N-oxide                                                      132-137                                                                            C.sub.12 H.sub.9 Cl.sub.2                                                                             X                29  2-(2,6-dichlorophenylmethylthio)pyridine N-oxide                                                          240-241                                                                            C.sub.12 H.sub.9 Cl.sub.2 NOS                                                                         X                30  2-(2,4,6-trimethylphenylmethylthio)pyridine N-oxide                                                       137-138                                                                            C.sub.15 H.sub.17 NOS   X                31  2-(2,4,6-trimethylphenylmethylsulfonyl)pyridine                                                           173-175                                                                            C.sub.15 H.sub.17 NO.sub.3 S                                                           ##STR20##                                                                         ##STR21##                                                                         ##STR22##                                                                            X                32  2-(2,6-dichlorophenylmethylsulfonyl)pyridine N-oxide                                                      214-216                                                                            C.sub.12 H.sub.9 Cl.sub.2 NO.sub.3                                                     ##STR23##                                                                         ##STR24##                                                                         ##STR25##                                                                            X                33  2-([3-trifluoromethylphenyl]methylsulfonyl)                                                               125-127                                                                            C.sub.13 H.sub.10 F.sub.3 NO.sub.3                                                     ##STR26##                                                                         ##STR27##                                                                         ##STR28##                                                                            X                    pyridine N-oxide                                                          34  2-(2,4-dichlorophenylmethylsulfonyl)pyridine N-oxide                                                      154-156                                                                            C.sub.12 H.sub.9 Cl.sub.2 NO.sub.3                                                                    X                35  2-(1-phenylethylsulfonyl)pyridine N-oxide                                                                 141-143                                                                            C.sub.13 H.sub.13 NO.sub.3 S                                                           ##STR29##                                                                         ##STR30##                                                                         ##STR31##                                                                            X                36  2-(2,4-dichlorophenylmethylthio)pyridine N-oxide                                                          173-174                                                                            C.sub.12 H.sub.9 Cl.sub.2 NOS                                                                         X                37  2-([2-methoxy-5-nitrophenyl]methylsulfonyl)                                                               226-227                                                                            C.sub.13 H.sub.10 N.sub.2 O.sub.6                                                                     X                    pyridine N-oxide                                                          38  2-(3,4-dimethylphenylmethylthio)pyridine N-oxide                                                          193-195                                                                            C.sub.14 H.sub.15 NOS   X                39  2-(isopropylenesulfonyl)pyridine N-oxide                                                                  Oil  C.sub.9 H.sub.11 NO.sub.3 S                                                                           X                40  2-(phenylethylthio)pyridine N-oxide                                                                       118-120                                                                            C.sub.13 H.sub.13 NOS   X                41  2-(phenylethylsulfonyl)pyridine N-oxide                                                                    99-100                                                                            C.sub.13 H.sub.13 NO.sub.3 S                                                                          X                42  2-(2,6-dichlorophenylmethylsulfinyl)pyridine                                                              135-137                                                                            C.sub.12 H.sub. 9 Cl.sub.2 NO.sub.2                                           S                                                                                      ##STR32##                                                                         ##STR33##                                                                         ##STR34##                                                                            X                    N-oxide                                                                   43  2-(2-fluorophenylmethylthio)pyridine N-oxide                                                              135-137                                                                            C.sub.12 H.sub.13 FNOS  X                44  2-[(3,4-dioxymethylene-6-chlorophenyl)methyl-                                                             179-180                                                                            C.sub.13 H.sub.10 ClNO.sub.5                                                           ##STR35##                                                                         ##STR36##                                                                         ##STR37##                                                                            X                    sulfonyl]pyridine N-oxide                                                 45  2-(2-fluorophenylmethylsulfonyl)pyridine N-oxide                                                          151-153                                                                            C.sub.12 H.sub.10 FNO.sub.3 S                                                          ##STR38##                                                                         ##STR39##                                                                         ##STR40##                                                                            X                46  2-(1-ethylpentylsulfonyl)pyridine N-oxide                                                                 Oil  C.sub.12 H.sub.19 NO.sub.3 S                                                                          X                47  2-(2-ethylphenylmethylsulfonyl)pyridine N-oxide                                                           -    C.sub.14 H.sub.15 NO.sub.3 S                                                                          X                48  2-(2-hexylsulfonyl)pyridine N-oxide                                                                       71-73                                                                              C.sub.12 H.sub.15 NO.sub.3 S                                                                          X                49  2-(cyclohexylsulfonyl)pyridine N-oxide                                                                    135-138                                                                            C.sub. 11 H.sub.15 No.sub. 3                                                                          X                50  2-(2,5-dimethylphenylmethylsulfinyl)pyridine                                                              142-144                                                                            C.sub.14 H.sub.15 NO.sub.3 S                                                           ##STR41##                                                                         ##STR42##                                                                         ##STR43##                                                                            X                51  2-(2-propylthio)pyridine N-oxide                                                                          77-79                                                                              C.sub.8 H.sub.11 NOS    X                52  2-(2-cyanophenylmethylthio)pyridine N-oxide                                                               154-157                                                                            C.sub.13 H.sub.10 N.sub.2 OS                                                                          X                53  2-(cycloheptylsulfonyl)pyridine N-oxide                                                                   103-107                                                                            C.sub.12 H.sub.17 NO.sub.3 S                                                           ##STR44##                                                                         ##STR45##                                                                         ##STR46##                                                                            X                54  2-(2-cyanophenylmethylsulfonyl)pyridine N-oxide                                                           188-190                                                                            C.sub.13 H.sub.10 FN.sub.2 O.sub.3                                                     ##STR47##                                                                         ##STR48##                                                                         ##STR49##                                                                            X                55  2-(2-propylsulfonyl)pyridine N-oxide                                                                      110-114                                                                            C.sub.8 H.sub.11 NO.sub.3 S                                                            ##STR50##                                                                         ##STR51##                                                                         ##STR52##                                                                            X                56  2-(cycloheptylthio)pyridine N-oxide                                                                       128-131                                                                            C.sub.12 H.sub.17 NOS   X                57  2-(2,4-dichlorophenylmethylsulfinyl)pyridine                                                              138-141                                                                            C.sub.12 H.sub.9 CL.sub.2 NO.sub.2                                                                    X                58  2-(phenylethylsulfinyl)pyridine N-oxide                                                                   Oil  C.sub.13 H.sub.13 NO.sub.2 S                                                                          X                59  2-[(3-trifluoromethylphenyl)methylsulfinyl]-                                                              104-108                                                                            C.sub.13 N.sub.10 F.sub.3 NO.sub.2                                                     ##STR53##                                                                         ##STR54##                                                                         ##STR55##                                                                            X                    pyridine N-oxide                                                          60  2-(4-methoxyphenylmethylsulfinyl)pyridine N-oxide                                                         140-148                                                                            C.sub.13 H.sub.13 NO.sub.3 S                                                                          X                61  2-(phenylmethylsulfinyl)pyridine N-oxide                                                                  119-122                                                                            C.sub.12 H.sub.11 NO.sub.2 S                                                                          X                62  2-(3-methylphenylmethylthio)pyridine N-oxide                                                              107-109                                                                            C.sub.13 H.sub.13 NOS   X                63  2-(3-methylphenylmethylsulfinyl)pyridine N-oxide                                                          67-71                                                                              C.sub.13 H.sub.13 NO.sub.2 S                                                           ##STR56##                                                                         ##STR57##                                                                         ##STR58##                                                                            X                64  2-(3-methylphenylmethylsulfonyl)pyridine N-oxide                                                          171-173                                                                            C.sub.13 H.sub.13 NO.sub.3 S                                                                          X                65  2-(2,4,6-trimethylphenylmethylsulfinyl)pyridine                                                           164-166                                                                            C.sub.15 H.sub.17 NO.sub.2 S                                                           ##STR59##                                                                         ##STR60##                                                                         ##STR61##                                                                            X                    N-oxide                                                                   66  2-(2-chlorophenylmethylsulfinyl)pyridine N-oxide                                                          124-127                                                                            C.sub.12 H.sub.10 ClNO.sub.2                                                           ##STR62##                                                                         ##STR63##                                                                         ##STR64##                                                                            X                67  2-(3,4-dimethylphenylmethylsulfinyl)pyridine                                                              123-126                                                                            C.sub.14 H.sub.15 NO.sub.2 S                                                           ##STR65##                                                                         ##STR66##                                                                         ##STR67##                                                                            X                    N-oxide                                                                   68  2-(2-methylphenylmethylsulfinyl)pyridine N-oxide                                                          99-102                                                                             C.sub.13 H.sub.13 NO.sub.2 S                                                           ##STR68##                                                                         ##STR69##                                                                         ##STR70##                                                                            X                69  2-(2-cyanophenylmethylsulfinyl)pyridine N-oxide                                                           158-161                                                                            C.sub.13 H.sub.10 N.sub.2 O.sub.2                                                      ##STR71##                                                                         ##STR72##                                                                         ##STR73##                                                                            X                70  2-(4-methylphenylmethylsulfinyl)pyridine N-oxide                                                          101-103                                                                            C.sub.13 H.sub.13 NO.sub.2 S                                                           ##STR74##                                                                         ##STR75##                                                                         ##STR76##                                                                            X                71  2-(3-fluorophenylmethylsulfonyl)pyridine N-oxide                                                          138-140                                                                            C.sub.12 H.sub.10 FNO.sub.3 S                                                                         X                72  2-(4-fluorophenylmethylsulfinyl)pyridine N-oxide                                                          100-103                                                                            C.sub.12 H.sub.10 FNO.sub.2 S                                                                         X                73  2-(4-fluorophenylmethylsulfonyl)pyridine N-oxide                                                          136-138                                                                            C.sub.12 H.sub.10 FNO.sub.2 S                                                                         X                74  2-(3-fluorophenylmethylsulfinyl)pyridine N-oxide                                                          70-74                                                                              C.sub.12 H.sub.10 FNO.sub.2 S                                                                         X                75  2-(2-fluorophenylmethylsulfinyl)pyridine N-oxide                                                          110-113                                                                            C.sub.12 H.sub.10 FNO.sub.2 S                                                          ##STR77##                                                                         ##STR78##                                                                         ##STR79##                                                                            X                76  2-(2-oxo-2-phenylethylsulfinyl)pyridine N-oxide                                                           121-123                                                                            C.sub.13 H.sub.11 NO.sub.3 S                                                                          X                77  2-(2-oxo-2-phenylethylsulfonyl)pyridine N-oxide                                                           117-120                                                                            C.sub.13 H.sub.11 NO.sub.4 S                                                           ##STR80##                                                                         ##STR81##                                                                         ##STR82##                                                                            X                78  2-(1-[4-chlorophenyl]ethylthio)pyridine N-oxide                                                           106-108                                                                            C.sub.13 H.sub.12 ClNOS                                                                ##STR83##                                                                         ##STR84##                                                                         ##STR85##                                                                            X                79  2-[1-(4-chlorophenyl)ethylsulfonyl]pyridine N-oxide                                                       188-191                                                                            C.sub.13 H.sub.12 ClNO.sub.3                                                                          X                80  2-(1-phenylbutylthio)pyridine N-oxide                                                                     130-132                                                                            C.sub.15 H.sub.17 NOS                                                                  ##STR86##                                                                         ##STR87##                                                                         ##STR88##                                                                            X                81  2-(1-[4-methylphenyl]ethylthio)pyridine N-oxide                                                           83-85                                                                              C.sub.14 H.sub.15 NOS                                                                  ##STR89##                                                                         ##STR90##                                                                         ##STR91##                                                                            X                82  2-(pentachlorophenylmethylthio)pyridine N-oxide                                                           183-185                                                                            C.sub.12 H.sub.2 Cl.sub.5 NOS                                                                         X                83  2-(2,3,6-trichlorophenylmethylthio)pyridine                                                               232-234                                                                            C.sub.12 H.sub.8 Cl.sub.3 NOS                                                                         X                    N-oxide                                                                   84  2-(4-cyanophenylmethylthio)pyridine N-oxide                                                               159-160                                                                            C.sub.13 H.sub.10 N.sub.2 OS                                                                          X                85  2-(2-oxo-2[p-2',2'-dichlorocyclopropylphenyl]-                                                            163-165                                                                            C.sub.16 H.sub.13 Cl.sub.2 NO.sub.2                                           S                       X                    ethylthio)pyridine N-oxide                                                86  2-(2-oxo-2[2,4-dimethylphenyl]ethylthio)pyridine                                                          106-108                                                                            C.sub.15 H.sub.15 NO.sub.2 S                                                                          X                    N-oxide                                                                   87  2-(1-[2-naphthyl]ethylthio)pyridine N-oxide                                                               112-115                                                                            C.sub.17 H.sub.15 NOS                                                                  ##STR92##                                                                         ##STR93##                                                                         ##STR94##                                                                            X                88  2-(2-methoxy-5-methylphenylmethylsulfonyl)-                                                               115-118                                                                            C.sub.14 H.sub.15 NO.sub.4 S                                                                          X                    pyridine N-oxide                                                          89  2-(2-bromo-5-methoxyphenylmethylsulfonyl)pyridine                                                         157-158                                                                            C.sub.13 H.sub.12 BrNO.sub.4                                                                          X                    N-oxide                                                                   90  2-(pentachlorophenylmethylsulfonyl)pyridine                                                               235-238                                                                            C.sub.12 H.sub.6 Cl.sub.5 NO.sub.3                                                                    X                    N-oxide                                                                   91  2-(pentachlorophenylmethylsulfinyl)pyridine                                                               213-215                                                                            C.sub.12 H.sub.6 Cl.sub.5 NO.sub.2                                                                    X                    N-oxide                                                                   92  2-(2,3,6-trichlorophenylmethylsulfonyl)pyridine                                                           194-196                                                                            C.sub.12 H.sub.6 Cl.sub.5 NO.sub.2                                                                    X                92  2-(2,3,6-trichlorophenylmethylsulfonyl)pyridine                                                           194-196                                                                            C.sub.12 H.sub.8 Cl.sub.3 NO.sub.3                                                                    X                    N-oxide                                                                   94  2-(2,3,6-trichlorophenylmethylsulfinyl)pyridine                                                           168-170                                                                            C.sub.12 H.sub.8 Cl.sub.3 NO.sub.2                                                     ##STR95##                                                                         ##STR96##                                                                         ##STR97##                                                                            X                    N-oxide                                                                   95  2-(4-cyanophenylmethylsulfonyl)pyridine N-oxide                                                           215-217                                                                            C.sub.13 H.sub.10 N.sub.2 O.sub.3                                                                     X                96  2-(4-cyanophenylmethylsulfinyl)pyridine N-oxide                                                           155-158                                                                            C.sub.13 H.sub.10 N.sub.2 O.sub.2                                                                     X                97  2-(2-oxo-2-[2,4-dimethylphenyl]ethylsulfonyl) pyridine                                                    149-152                                                                            C.sub.15 H.sub.15 NO.sub.4 S                                                                          X                    N-oxide                                                                   98  2-(2-oxo-2[2,4-dimethylphenyl]ethylsulfinyl)-                                                             145-147                                                                            C.sub.15 H.sub.15 NO.sub.3 S                                                                          X                    pyridine N-oxide                                                          99  2-(1-[2,5-dimethylphenyl]ethylthio)pyridine N-oxide                                                       118-120                                                                            C.sub.15 H.sub.17 NOS                                                                  ##STR98##                                                                         ##STR99##                                                                         ##STR100##                                                                           X                100 2-(1-[4-bromophenyl]ethylthio)pyridine N-oxide                                                            113-115                                                                            C.sub.13 H.sub.12 BrNOS                                                                ##STR101##                                                                        ##STR102##                                                                        ##STR103##                                                                           X                101 2-(2,5-diisopropylphenylmethylsulfonyl)pyridine                                                           120-123                                                                            C.sub.18 H.sub.23 NO.sub.3 S                                                           ##STR104##                                                                        ##STR105##                                                                        ##STR106##                                                                           X                    N-oxide                                                                   102 2-(2,5-diisopropylphenylmethylsulfinyl)pyridine                                                           83-86                                                                              C.sub.18 H.sub.23 NO.sub.2 S                                                                          X                    N-oxide                                                                   103 2-(2-oxo-2[p-2',2'-dichlorocyclopropylphenyl]-                                                            96-99                                                                              C.sub.16 H.sub.13 Cl.sub.2 NO.sub.3                                           S                                                                                      ##STR107##                                                                        ##STR108##                                                                        ##STR109##                                                                           X                    ethylsulfonyl)pyridine N-oxide                                            104 2-(1-phenylbutylsulfonyl)pyridine N-oxide                                                                 145-148                                                                            C.sub.15 H.sub.17 NO.sub.3                                                             ##STR110##                                                                        ##STR111##                                                                        ##STR112##                                                                           X                105 2-[1-(4-methylphenyl)ethylsulfonyl]pyridine                                                               158-160                                                                            C.sub.14 H.sub.15 NO.sub.3 S                                                           ##STR113##                                                                        ##STR114##                                                                        ##STR115##                                                                           X                    N-oxide                                                                   106 2-[1-(4-methylphenyl)ethylsulfinyl]pyridine                                                               121-123                                                                            C.sub.14 H.sub.15 NO.sub.2 S                                                                          X                    N-oxide                                                                   107 2-[1-(2-thienyl)ethylsulfonyl]pyridine N-oxide                                                            147-149                                                                            C.sub.11 H.sub.11 NO.sub.3 S.sub.2                                                     ##STR116##                                                                        ##STR117##                                                                        ##STR118##                                                                           x                108 2-[1-(4-fluorophenyl)ethylsulfoyl]pyridine                                                                142-144                                                                            C.sub.13 H.sub.12 FNO.sub.3 S                                                          ##STR119##                                                                        ##STR120##                                                                        ##STR121##                                                                           X                    N-oxide                                                                   109 2-[1-(2,5-dimethylphenyl)ethylsulfonyl]pyridine                                                           160-163                                                                            C.sub.15 H.sub.17 NO.sub.3 S                                                                          X                    N-oxide                                                                   110 2-(1-phenylpropylthio)pyridine N-oxide                                                                    158-160                                                                            C.sub.14 H.sub.15 NOS                                                                  ##STR122##                                                                        ##STR123##                                                                        ##STR124##                                                                           X                111 2-(1-[3,4-dichlorophenyl]ethylthiopyridine N-oxide                                                        Oil  C.sub.13 H.sub.11 Cl.sub.2 NOS                                                         ##STR125##                                                                        ##STR126##                                                                        ##STR127##                                                                           X                112 2-(3,4-dioxymethylenephenylmethylthio)pyridine                                                            146-148                                                                            C.sub.13 H.sub.11 NO.sub.3 S                                                                          X                    N-oxide                                                                   113 2-[1-(4-fluorophenyl)ethylsulfinyl]pyridine                                                                98-101                                                                            C.sub.13 H.sub.12 FNO.sub.2 S                                                          ##STR128##                                                                        ##STR129##                                                                        ##STR130##                                                                           X                    N-oxide                                                                   114 2-[1-(2-naphthyl)ethylsulfonyl]pyridine N-oxide                                                           144-146                                                                            C.sub.17 H.sub.15 NO.sub.3                                                                            X                115 2-(1-[2,5-dimethylphenyl]octylthio)pyridine                                                               92-94                                                                              C.sub.21 H.sub.29 NOS                                                                  ##STR131##                                                                        ##STR132##                                                                        ##STR133##                                                                           X                    N-oxide                                                                   116 2-(1-(4-bromophenyl)ethylsulfinyl]pyridine N-oxide                                                        177-180                                                                            C.sub.13 H.sub.12 BrNO.sub.2                                                                          X                117 2-[1-(4-brommophenyl)ethylsulfonyl]pyridine N-oxide                                                       193-195                                                                            C.sub.13 H.sub.12 BrNO.sub.3                                                           ##STR134##                                                                        ##STR135##                                                                        ##STR136##                                                                           X                118 2-(1-phenylpropylsulfonyl)pyridine N-oxide                                                                144-146                                                                            C.sub.14 H.sub.15 NO.sub.3 S                                                           ##STR137##                                                                        ##STR138##                                                                        ##STR139##                                                                           X                119 2-(2-oxo-2-[2,5-dimethylphenyl]ethylthio)-                                                                63-66                                                                              C.sub.15 H.sub.15 NO.sub.2 S                                                           ##STR140##                                                                        ##STR141##                                                                        ##STR142##                                                                           X                    pyridine N-oxide                                                          120 2-(2-oxo-2-[4-fluorophenyl]ethylsulfinyl)pyridine                                                         150-152                                                                            C.sub.13 H.sub.10 FNO.sub.3 S                                                                         X                    N-oxide                                                                   121 2-83,4-dichlorophenylmethylsulfinyl)pyridine                                                              133-135                                                                            C.sub.12 H.sub.9 Cl.sub.2 NO.sub.2                                                     ##STR143##                                                                        ##STR144##                                                                        ##STR145##                                                                           X                    N-oxide                                                                   122 2-(1-[2,5-dimethylphenyl]dodecylthio)pyridine                                                             90-92                                                                              C.sub.25 H.sub.37 NOS                                                                  ##STR146##                                                                        ##STR147##                                                                        ##STR148##                                                                           X                    N-oxide                                                                   123 2-83-bromophenylmethylthio)pyridine N-oxide                                                               132-134                                                                            C.sub.12 H.sub.10 BrNOS X                124 2-(3-bromophenylmethylsulfonyl)pyridine N-oxide                                                           145-147                                                                            C.sub.12 H.sub.10 BrNO.sub.3                                                                          X                125 2-(3-bromophenylmethylsulfinyl)pyridine N-oxide                                                           155  C.sub.12 H.sub.10 BrNO.sub.2                                                                          X                126 2-(1-[3,4-dichlorophenyl]ethylsulfonyl)pyridine                                                           129-134                                                                            C.sub.3 H.sub.11 Cl.sub.2 NO.sub.3                                                                    X                    N-oxide                                                                   127 2-(2-oxo-2-[2,5-dimethylphenyl]ethylsulfonyl)-                                                            142-144                                                                            C.sub.15 H.sub.15 NO.sub.4 S                                                                          X                    pyridine N-oxide                                                          128 2-(2-oxo-2-[2,5-dimethylphenyl]ethylsulfinyl)-                                                            153-155                                                                            C.sub.15 H.sub.15 NO.sub.                                                                             X S                  pyridine N-oxide                                                          129 2-(3,4-methylenedioxyphenylmethylsulfinyl)-                                                               171-173                                                                            C.sub.13 H.sub.11 NO.sub.4 S                                                                          X                    pyridine N-oxide                                                          130 2-83,4-methylenedioxyphenylmethylsulfoyl)-                                                                163-165                                                                            C.sub.13 H.sub.10 NO.sub.5 S                                                                          X                    pyridine N-oxide                                                          131 2-(2-oxo-2-[2,5-diisopropylphenyl]ethylsulfinyl)-                                                         116-118                                                                            C.sub.19 H.sub.23 NO.sub.3 S                                                                          X                    pyridine N-oxide                                                          132 2-(2-pyridylsulfonyl)propinonic acid ethyl ester                                                          109-110                                                                            C.sub.10 H.sub.13 NO.sub.5 S                                                                          X                133 2-(2-oxo-2-phenyl-1-methylethylsulfinyl)pyridine                                                          120-124                                                                            C.sub.14 H.sub.13 NO.sub.3 S                                                                          X                    N-oxide                                                                   134 2-(2-oxo-2-phenyl)-1-methylethylsulfonyl)pyridine                                                         179-182                                                                            C.sub.14 H.sub.13 NO.sub.4 S                                                                          X                    N-oxide                                                                   135 2-(1-[2,3,6-trimethylphenyl]ethylthio)pyridine                                                            108-110                                                                            C.sub.15 H.sub.17 NOS   X                    N-oxide                                                                   136 2-(2-nitrophenylmethylthio)pyridine N-oxide                                                               120-123                                                                            C.sub.12 H.sub.10 N.sub.2 O.sub.3                                                                     X                137 2-(4-[2,2-dichlorocyclopropyl]phenylmethylthio)-                                                          122-127                                                                            C.sub.15 H.sub.13 Cl.sub.2 NOS                                                                        X                    pyridine N-oxide                                                          138 2-(2,3,6-trimethylphenylmethylsulfonyl)pyridine                                                           155  C.sub.15 H.sub.17 NO.sub.3 S                                                                          X                    N-oxide                                                                   139 2-(1-[2,4,6-trimethylphenyl]ethylsulfonyl)-                                                               172-175                                                                            C.sub.16 H.sub.19 NO.sub.3 S                                                                          X                    pyridine N-oxide                                                          140 2-(2-nitrophenylmethylsulfoyl)pyridine N-oxide                                                            155-158                                                                            C.sub.12 H.sub.11 N.sub.2 O.sub.5                                                                     X                141 2-(2-nitrophenylmethylsulfinyl)pyridine N-oxide                                                           165-167                                                                            C.sub.12 H.sub.11 N.sub.2 O.sub.3                                                                     X                142 2-(2,3,6-trimethylphenylmethylsulfinyl)pyridin                                                            72-75                                                                              C.sub.15 H.sub.18 NO.sub.2 S                                                                          X                    N-oxide                                                                   143 2-(2-methyl-1-naphthylmethylsulfonyl)pyridine                                                             195-198                                                                            C.sub.17 H.sub.17 NO.sub.3 S                                                                          X                    N-oxide                                                                   144 2-(2-methyl-1-naphthylmethylsulfinyl)pyridine                                                             122-125                                                                            C.sub.17 H.sub.15 NO.sub.2 S                                                                          X                    N-oxide                                                                   145 2-(α-[2-methylphenyl]phenylmethylsulfonyl)pyridine                                                  122-25                                                                             C.sub.19 H.sub.17 NO.sub.2 S                                                           ##STR149##                                                                        ##STR150##                                                                        ##STR151##                                                                           X                    N-oxide                                                                   146 2-(2-iodophenylmethylsulfonyl)pyridine N-oxide                                                            142-146                                                                            C.sub.12 H.sub.11 INO.sub.3 S                                                                         X                147 2-(2-iodophenylmethylsulfinyl)pyridine N-oxide                                                            160-163                                                                            C.sub.12 H.sub.11 INO.sub.2 S                                                                         X                148 2-(1-[4-nitrophenyl]ethylsulfonyl)pyridine N-oxide                                                        167-171                                                                            C.sub. 13 H.sub.12 N.sub.2 O.sub.5                                                                    X                149 2-(4-[2,2-dichloropropyl]phenylmethylsul-                                                                 oil  C.sub.15 H.sub.13 Cl.sub.2 NO.sub.3                                           S                       X                    fonyl)pyridine N-oxide                                                    150 2-(4-[2,2-dichlorocyclopropyl]phenylmethylsul-                                                            oil  C.sub.15 H.sub.13 Cl.sub.2 NO.sub.2                                           S                       X                    finyl)pyridine N-oxide                                                    151 2-(1-[1-naphthyl]ethylsulfonyl)pyridine N-oxide                                                           wax  C.sub.17 H.sub.15 NO.sub.3 S                                                                          X                152 2-[1-(1-naphthyl)ethylsulfinyl]                                                                           127-130                                                                            C.sub.17 H.sub.15 NO.sub.2 S                                                                          X                    pyridine N-oxide                                                          153 2-(3,4-dimethoxyphenylmethylthio)pyridine N-oxide                                                         141-143                                                                            C.sub.14 H;hd 15NO.sub.3 S                                                             ##STR152##                                                                        ##STR153##                                                                        ##STR154##                                                                           X                154 2-(3,4-dimethoxyphenylmethylsulfinyl)pyridine                                                             133-135                                                                            C.sub.14 H.sub.15 NO.sub.4 S                                                                          X                    N-oxide                                                                   155 2-(3,4-dimethoxyphenylmethylsulfonyl)pyridine                                                             159-161                                                                            C.sub.14 H.sub.15 NO.sub.5 S                                                                          X                    N-oxide                                                                   156 2-(1-[2,5-diethylphenyl]ethylsulfonyl)pyridine                                                            124-127                                                                            C.sub.17 H.sub.21 NO.sub.3 S                                                                          X                    N-oxide                                                                   157 2-(1-[2,5-diisopropylphenyl]ethylthio)pyridine                                                            124-126                                                                            C.sub.19 H.sub.25 NOS                                                                  ##STR155##                                                                        ##STR156##                                                                        ##STR157##                                                                           X                    N-oxide                                                                   158 2-(cyclopentylsulfinyl)pyridine N-oxide                                                                   80-82                                                                              C.sub.10 H.sub.13 NO.sub.2 S                                                                          X                159 2-(cyclopentylsulfonyl)pyridine N-oxide                                                                   107-109                                                                            C.sub.10 H.sub.13 NO.sub.3 S                                                                          X                160 2-(2,5-dimethoxyphenylmethylsulfoyl)pyridine                                                              129-132                                                                            C.sub.14 H.sub.15 NO.sub.5 S                                                                          X                    N-oxide                                                                   161 2-(2,5-dimethoxyphenylmethylsulfinyl)pyridine                                                             136-138                                                                            C.sub.14 H.sub.15 NO.sub.4 S                                                                          X                    N-oxide                                                                   162 2-(2-ethoxyphenylmethylsulfinyl)pyridine                                                                  135-138                                                                            C.sub.14 H.sub.15 NO.sub.3 S                                                                          X                    N-oxide                                                                   163 2-(2-ethoxyphenylmethylsulfonyl)pyridine                                                                  145-147                                                                            C.sub.14 H.sub.15 NO.sub.4 S                                                                          X                    N-oxide                                                                   164 2-1-[2-chloro-4-methylphenyl]ethylthio)-                                                                  118-120                                                                            C.sub.14 H.sub.14 ClNOS                                                                ##STR158##                                                                        ##STR159##                                                                        ##STR160##                                                                           X                    pyridine N-oxide                                                          165 2-(1-[2-chloro-4-methylphenyl]ethylsulfonyl)-                                                             166-168                                                                            C.sub.14 H.sub.14 ClNO.sub.3                                                           ##STR161##                                                                        ##STR162##                                                                        ##STR163##                                                                           X                    pyridine N-oxide                                                          166 2-(1-[2-chloro-4-methylphenyl]ethylsulfinyl)-                                                             121-123                                                                            C.sub.14 H.sub.14 CNO.sub.2 S                                                          ##STR164##                                                                        ##STR165##                                                                        ##STR166##                                                                           X                    pyridine N-oxide                                                          167 2-(1-[2-chloro-5-methylphenyl]ethylthio0-                                                                 112-114                                                                            C.sub.14 H.sub.14 ClNOS                                                                ##STR167##                                                                        ##STR168##                                                                        ##STR169##                                                                           X                    pyridine N-oxide                                                          168 2-(1-[2,5-diisopropylphenyl]ethylsulfonyl)-                                                               123-127                                                                            C.sub.19 H.sub.25 NO.sub.3 S                                                                          X                    pyridine N-oxide                                                          169 2-(2,3,5,6-tetrachloro-4-methylphenylmethylthio)-                                                         178-180                                                                            C.sub.13 H.sub.9 Cl.sub.4 NOS                                                                         X                    pyridine N-oxide                                                          170 2-(2,3,5,6-tetrachloro-4-methylphenylmethyl-                                                              204-205                                                                            C.sub.13 H.sub.9 Cl.sub.4 NO.sub.2                                                                    X                    sulfinyl)pyridine N-oxide                                                 171 2-(2,3,5,6-tetrachloro-4-methylphenylmethyl-                                                              215-218                                                                            C.sub. 13 H.sub.9 Cl.sub.4 NO.sub.3                                           S                       X                    sulfonyl)pyridine N-oxide                                                 172 2-(1-[2,5-dichlorophenyl]ethylthio)pyridine                                                               145-147                                                                            C.sub.13 H.sub.11 Cl.sub.2 NOS                                                         ##STR170##                                                                        ##STR171##                                                                        ##STR172##                                                                           X                    N-oxide                                                                   173 2-(1-[2-chloro-5-methylphenyl]ethylsulfinyl)-                                                             125-127                                                                            C.sub.14 H.sub.14 ClNO.sub.2                                                           ##STR173##                                                                        ##STR174##                                                                        ##STR175##                                                                           X                    pyridine N-oxide                                                          174 2-(1-[2-chloro-5-methylphenyl]ethylsulfonyl)-                                                             175-177                                                                            C.sub.14 H.sub.14 ClNO.sub.3                                                           ##STR176##                                                                        ##STR177##                                                                        ##STR178##                                                                           X                    pyridine N-oxide                                                          175 2-(1-[2,5-dichlorophenyl]ethylsulfinyl)pyridine                                                           127-128                                                                            C.sub.13 H.sub.11 Cl.sub.2 NO.sub.2                                           S                                                                                      ##STR179##                                                                        ##STR180##                                                                        ##STR181##                                                                           X                    N-oxide                                                                   176 2-(1-[2,5-dichlorophenyl]ethylsulfonyl)pyridine                                                           158-160                                                                            C.sub.13 H.sub.11 Cl.sub.2 NO.sub.3                                           S                                                                                      ##STR182##                                                                        ##STR183##                                                                        ##STR184##                                                                           X                    N-oxide                                                                   177 2-(-1[2,4,5-trimethylphenyl]ethylsulfinyl)-                                                               134-137                                                                            C.sub.16 H.sub.19 NO.sub.2                                                                            X                    pyridine N-oxide                                                          178 2-(1-[2,4,5-trimethylphenyl]ethylsulfonyl)-                                                               132-134                                                                            C.sub.16 H.sub.19 NO.sub.3 S                                                                          X                    pyridine N-oxide                                                          179 2-(1-[2,3,4-trimethylphenyl]ethylsulfinyl)-                                                               164-167                                                                            C.sub.16 H.sub.19 NO.sub.2 S                                                                          X                    pyridine N-oxide                                                          180 2-(1-[2,3,4-trimethylphenyl]ethylsulfonyl)-                                                               155-158                                                                            C.sub.16 H.sub.19 NO.sub.3 S                                                                          X                    pyridine N-oxide                                                          181 2-(1-[2,3,4,5-tetramethylphenyl]ethylsulfinyl)-                                                           185-190                                                                            C.sub.17 H.sub.21 NO.sub.2 S                                                                          X                    pyridine N-oxide                                                          182 2-(1-[2,3,4,5-tetramethylphenyl]ethylsulfonyl)-                                                           145-150                                                                            C.sub.17 H.sub.21 NO.sub.3 S                                                                          X                    pyridine N-oxide                                                          183 2-(3,4,5-trimethoxyphenylmethylsulfinyl)-                                                                 144-146                                                                            C.sub.15 H.sub.17 NO.sub.5 S                                                           ##STR185##                                                                        ##STR186##                                                                        ##STR187##                                                                           X                    pyridine N-oxide                                                          184 2-(3,4,5-trimethoxyphenylmethylsulfonyl)-                                                                 153-155                                                                            C.sub.15 H.sub.17 NO.sub.6 S                                                           ##STR188##                                                                        ##STR189##                                                                        ##STR190##                                                                           X                    pyridine N-oxide                                                          185 2-(9-anthranylmethylsulfinyl)pyridine N-oxide                                                             150-153                                                                            C.sub.20 H.sub.15 NO.sub.2 S                                                                          X                186 2-(2-thienylmethylthio)pyridine N-oxide                                                                   166-170                                                                            C.sub.10 H.sub.9 NOS.sub.2                                                                            X                187 2-(2-thienylmethylsulfinyl)pyridine N-oxide                                                               115-119                                                                            C.sub.10 H.sub.9 NO.sub.2 S.sub.2                                                                     X                188 2-(2-thienylmethylsulfonyl)pyridine N-oxide                                                               90-97                                                                              C.sub.10 H.sub.9 NO.sub.3 S.sub.2                                                                     X                189 2-(1-phenylethylsulfinyl)pyridine N-oxide                                                                 130-131                                                                            C.sub.13 H.sub.13 NO.sub.2 S                                                                          X                190 2-(1-[2,5-dimethylphenyl]ethylsulfinyl)pyridine                                                           126-127                                                                            C.sub.15 H.sub.17 NO.sub.2 S                                                                          X                    N-oxide                                                                   191 2-(1-[4-chlorophenyl]ethylsulfinyl)pyridine                                                               130-131                                                                            C.sub.13 H.sub.12 ClNO.sub.2                                                                          X                    N-oxide                                                                   192 2-(1-[2,4-dichloro-3-methyl]ethylsul-                                                                     192-194                                                                            C.sub. 14 H.sub.13 Cl.sub.2 NO.sub.3                                          S                       X                    fonyl)pyridine N-oxide                                                    193 2-(1-[2,4-dichloro-3-methylphenyl]ethylsul-                                                               147-148                                                                            C.sub.14 H.sub.13 Cl.sub.2 NO.sub.2                                           S                       X                    finyl)pyridine N-oxide                                                    194 2-(1-phenyl-2-propylthio)pyridine N-oxide                                                                 125-127                                                                            C.sub.14 H.sub.15 NOS   X                195 2-(3-methyl-1-[2,5-dimethylphenyl]butyl-                                                                  185-187                                                                            C.sub.18 H.sub.23 NO.sub.3 S                                                                          X                    sulfonyl)pyridine N-oxide                                                 196 2-(1-phenyl-2-propylsulfonyl)pyridine N-oxide                                                              99-10                                                                             C.sub.14 H.sub.15 NO.sub.3 S                                                                          X                197 2-(1-phenyl-2-propylsulfinyl)pyridine N-oxide                                                             Oil  C.sub.14 H.sub.15 NO.sub.2 S                                                                          X                198 2-(1-[2,5-dichlorothienyl-3-]ethylthio)pyridine                                                           129-133                                                                            C.sub.11 H.sub.9 Cl.sub.2 NOS.sub.2                                                                   X                    N-oxide                                                                   199 2-(1-[(2,5-dimethylphenyl]-2-phenylethylthio)-                                                            Oil  C.sub.21 H.sub.21 NOS   X                    pyridine N-oxide                                                          200 2-(4-vinylphenylmethylthio)pyridine N-oxide                                                               103-105                                                                            C.sub.14 H.sub.13 NOS   X                201 2-(4-vinylphenylmethylsulfinyl)pyridine N-oxide                                                           Oil  C.sub.14 H.sub.13 NO.sub.2 S                                                                          X                202 2-(4-biphenylmethylthio)pyridine N-oxide                                                                  130-132                                                                            C.sub.19 H.sub.17 NOS   X                203 2-(1-[4-phenoxyphenyl]ethylthio)pyridine                                                                  Oil  C.sub. 19 H.sub.17 NO.sub.2 S                                                                         X                    N-oxide                                                                   204 2-(1-[4-phenoxyphenyl]ethylsulfoyl)pyridine                                                               Oil  C.sub.19 H.sub.17 NO.sub.4 S                                                                          X                    N-oxide                                                                   205 2-(2-methyl-5-isopropylphenylmethylthio)pyridine                                                          Oil  C.sub.17 H.sub.21 NOS   X                    N-oxide                                                                   206 2-(2-methyl-5-isopropylphenylmethylsulfonyl)-                                                             Oil  C.sub.17 H.sub.21 NO.sub.3 S                                                                          X                    pyridine N-oxide                                                          207 2-(1-[5-indanyl]ethylthio)pyridine N-oxide                                                                Oil  C.sub.16 H.sub.17 NOS   X                208 2-(1-[5-indanyl]ethylsulfonyl)pyridine N-oxide                                                            138-140                                                                            C.sub.16 H.sub.17 NO.sub.3 S                                                                          X                209 2-(3-methyl-1-[2,5-dimethylphenyl]butylthio)-                                                             Oil  C.sub.18 H.sub.23 NOS   X                    pyridine N-oxide                                                          210 2-(1-[2,5-dimethylphenyl]butylthio)pyridine                                                               Oil  C.sub.17 H.sub.21 ONS   X                    N-oxide                                                                   212 2-[1-(p-chlorophenyl)octylthio]pyridine N-oxide                                                           71-73                                                                              C.sub.19 H.sub.24 ClNOS X                213 2-[1-(p-chlorophenyl)butylthio]pyridine N-oxide                                                           52-54                                                                              C.sub.15 H.sub.16 ClNOS X                214 2-[1-(p-chlorophenyl)dodecylthio]pyridine N-oxide                                                         69-71                                                                              C.sub.23 H.sub.32 ClNOS X                215 2-[1-(2-chloro-5-methylphenyl)octylthio)-                                                                 102-104                                                                            C.sub.20 H.sub.26 ClNOS                                                                ##STR191##                                                                        ##STR192##                                                                        ##STR193##                                                                        ##STR194##                                                                       X                    pyridine N-oxide                                                          217 2-[1-(2-naphthalene)octylthio]pyridine                                                                    75-76                                                                              C.sub.23 H.sub.27 NOS                                                                  ##STR195##                                                                        ##STR196##                                                                        ##STR197##                                                                        ##STR198##                                                                       X                    N-oxide                                                                   217 2-[1-(4-phenoxyphenyl)octylthio]pyridine                                                                  91-92                                                                              C.sub.25 H.sub.29 NO.sub.2 S                                                           ##STR199##                                                                        ##STR200##                                                                        ##STR201##                                                                        ##STR202##                                                                       X                    N-oxide                                                                   218 2-[1-(3,4,5-trimethylphenyl)octylthio]-                                                                   Oil  C.sub.22 H.sub.31 NOS   X                    pyridine N-oxide                                                          219 2-[1-(4-chlorophenyl)hexadecylthio]pyridine                                                               65-66                                                                              C.sub.27 H.sub.40 ClNOS                                                                ##STR203##                                                                        ##STR204##                                                                        ##STR205##                                                                        ##STR206##                                                                       X                    N-oxide                                                                   220 2-[1-(2,5-dimethylphenyl)hexadecylthio]-                                                                  81-83                                                                              C.sub.29 H.sub.45 NOS                                                                  ##STR207##                                                                        ##STR208##                                                                        ##STR209##                                                                        ##STR210##                                                                       X                    pyridine N-oxide                                                          __________________________________________________________________________

The following preparations illustrate methods of making typicalcompounds of Table I.

Compound 80

2-(1-Phenylbutylthio)pyridine N-oxide

A mixture of 16.9 gms (0.1 mol) of 1-phenylbutylchloride, 36 gms of a40% aqueous solution of the sodium salt of 2-mercaptopyridine N-oxide(0.1 mol) and 50 ml of ethanol was warmed and stirred at 50° to 60° C.for 2.5 hours. The cooled reaction mixture was poured into 500 ml ofwater with agitation. The precipitated product was filtered, washed withwater and dried. After recrystallization for ethanol a yield of 10 gms(45% theory) of white crystals was obtained.

Melting point 130°-132° C.

Analysis based on C₁₅ H₁₇ NOS--Calc: C 69.48; H 6.61; N 5.40. Found: C69.48; H 6.51; N 5.46.

Compound 139

2-(1-[2,4,6-Trimethylphenyl]ethylsulfonyl)pryridine N-oxide

To a vigorously stirred mixture of 5.6 gm (0.02 mol) of2-(1-[2,4,6-trimethylphenyl]ethylthio)pyridine N-oxide in 50 ml ofchloroform and 50 ml of phosphate buffer solution (pH 7.5) maintained at0° to 5° C. is slowly added 8 gm (0.04 mol) metachloroperoxybenzoic acid(85%) (MCPBA) in 100 ml of chloroform. After addition is completed thetemperature is allowed to become ambient. Stirring is continued for 16hours.

The chloroform layer is separated, washed with sodium bicarbonatesolution to remove the benzoic acid and dried over sodium sulfate.Removal of the chloroform yields on oil which crystallized uponstanding. Recrystallization from ethanol yields 3 gms (50% theory) orproduct.

Melting point 172° - 175° C.

IR: SO₂ 1310, 1140; NO 1270, 845 cm⁻¹.

Compound 68 2-(2-Methylphenylmethysulfinyl)pyridine N-oxide

To a vigorously stirred solution of 6.9 gm (0.03 mol) of2-(2-methylphenylmethylthio)pyridine N-oxide in 50 ml of chloroformmaintained at 0° to 10° C. is slowly added a solution of 6 gm (0.03 mol)MCPBA (85%) in 100 ml of chloroform. When addition is complete thetemperature is allowed to rise to ambient. After sixteen hours thereaction solution is washed up in the manner described in Example 139.

The resultant residual oil crystallizes upon standing and afterrecrystallizing from ethanol, 4.7 gm (58% theory) of product isobtained.

Melting point 99°-102° C.

Analysis based on C₁₃ H₁₃ NO₂ S--Calc: C 63.14; H 5.30; N 5.66. Found: C62.66; H 5.31; N 5.45.

Compound 140

2-(2-Nitrophenylmethylsulfonyl)pyridine N-oxide

The procedure employed is identical to that of Example 139 using 5.2 gm(0.02 mol) 2-(2-nitrophenylmethylthio)pyridine N-oxide in 50 mlchloroform with 5 gms (0.04 mol) MCPBA in 100 ml chloroform.

The crude product which is only sparingly soluble in hot ethanolrequired 300 ml for recrystallization to yield 5 gms (96% theory) ofproduct.

Melting point 155°-158° C.

IR: SO₂ 1330, 1140; NO 1280, 845 cm⁻¹.

Compound 115

2-(2-[2,5-Dimethylphenyl]octylthio)pyridine N-oxide

A mixture of 24 gm (0.1 mol) of 1-(2,5-dimethylphenyl)n-hexylchlorideand 36 gms of a 40% aqueous solution of the sodium salt of2-mercaptopyridine N-oxide in 50 ml of ethanol is heated with stirringat 60° to 70° for 1 hour. The ethanol is removed under vacuum and theresidual slurry extracted with two 75 ml portions of chloroform. Thechloroform solution is dried over sodium sulfate, filtered andevaporated to approximately 30 gms of crude material. Recrystallizationfrom ethyl acetate yields 23 gm (68% theory) of pure product.

Melting point 92°-94° C.

IR: NO 1255, 840; > 4CH₂ chain 710 cm⁻¹.

Compound 75

2-(2-Fluorophenylmethylsulfinyl)pyridine N-oxide

The procedure employed is identical to that of Example 68 using 5.7 gm(0.024 mol) 2-(2-fluorophenylmethylthio)pyridine N-oxide in 50 ml ofchloroform with 4.8 gm (0.024 mol) MCPBA in 75 ml chloroform.

The residual crude oil crystallizes upon standing and afterrecrystallization from ethanol yields 3.8 gm (65% theory) of product.

Melting point 110°-113° C.

Analysis based on C₁₂ H₁₁ FNO₂ S--Calc: C 57.36; H 4.01; N 5.58. Found:C 57.43; H 3.95; N 5.68.

Compound 96

2-(4-Cyanophenylmethylsulfinyl)pyridine N-oxide

The procedure employed is identical to that of Example 68 using 3.6 gm(0.015 mol) 2-(4-cyanophenylmethylthio)pyridine N-oxide in 50 ml ofchloroform with 3 gm (0.015 mol) MCPBA in 50 ml chloroform.

The crude product is recrystallized from ethanol to yield 215 gm (66%theory) of product.

Melting point 155°-158° C.

IR: NO 1240, 840; SO 1045 cm⁻¹.

Compound 50

2-(2,5-Dimethylphenylmethylsulfinyl)pyridine N-oxide

A vigorously stirred slurry consisting of 30 gm (0.12 mol)2-(2,5-dimethylphenylthio)pyridine N-oxide in 130 ml of 5% aqueousacetic acid and 0.3 gm of vanadium pentoxide is brought to 80° C. and 12gm (0.12 mol) of 30% hydrogen peroxide added slowly. The addition isexothermic necessitating some intermittent cooling to maintain thetemperature below 85° C. The addition requires about fifteen minutesduring which time the slurry changes to a homogeneous solution. Thereaction mixture is cooled down precipitating the solid sulfoxide.Filtration followed by water wash and drying yielded 30 gm (96% theory)of product.

Melting point 145°-147° C.

Analysis based on C₁₄ H₁₅ NO₂ S--Calc. C 64.34; H 5.75; N 5.36. Found: C64.43; H 5.67; N 5.13.

Compound 62

2-(3,4-Dimethylphenylmethylsulfinyl)pyridine N-oxide

The procedure employed is identical to that of Example 68 using 7.4 gm(0.03 mol) 2-(3,4-dimethylphenylmethylthio)pyridine N-oxide in 50 ml ofchloroform with 6 gm (0.03 mol) MCPBA (85%) in 100 ml chloroform.

The crude product is recrystallized from ethanol to yield 5.7 gm (75%theory) of product.

Melting point 123°-126° C.

Analysis based on C₁₄ H₁₅ NO₂ S--Calc: C 64.34; H 5.75; N 5.36. Found: C64.89; H 6.08; N 5.50.

Compound 128

2-(2-Oxo-2-[2,5-dimethylphenyl]ethylsulfinyl)pyridine N-oxide

The procedure employed is identical to that of Example 68 using 8.2 gm(0.03 mol) 2-(2-oxo-2-[2,5-dimethylphenyl]ethylthio)pyridine N-oxide in50 ml chloroform with 6 gm (0.03 mol) MCPBA (85%) in 100 ml chloroform.

The crude product is recrystallized from ethanol to yield 5.4 gm (64%theory) of product.

Melting point 153°-155° C. (decomp.).

IR: C = 0 1680, NO 1240, 845, SO 1055, 1075 (doublet) cm⁻¹.

Compound 6

2-(3,4-Dimethylphenylmethylsulfonyl)pyridine N-oxide

Twenty ml (0.2 mol) of 30% hydrogen peroxide is added slowly and withstirring to 11.5 gm (0.05 mol) of2-(3,4-dimethylphenylmethylthio)pyridine in 50 ml of glacial acetic acidmaintained at ambient temperature. After 1 hour the mixture is graduallyheated to 80°-85° C. and maintained for 10 hours. Cool and add an equalvolume of water. The volume is reduced by one-half by evaporation. Whenperoxide is detected in the residue with starch iodide paper thedilution and evaporation procedure is repeated, until the peroxide hasbeen removed. Evaporation is then carried to a residual oil which istaken up in 7:3 chloroform:acetone and chromotographed on a silica gelcolumn.

5.5 gms of product is isolated and recrystallized from ethanol (40%theory).

Melting point 165°-167° C.

Analysis based on C₁₄ H₁₅ NO₃ S--Calc: C 60.63; H 5.41; N 5.03; S 11.55.Found: C 60.77; H 5.73; N 4.98; S 11.73.

Compound 57

2-(2,4-Dichlorophenylmethylsulfinyl)pyridine N-oxide

The procedure employed is identical to that of Example 68 using 5.8 gm(0.02 mol) 2-(2,4-Dichlorophenylmethylthio)pyridine N-oxide in 50 ml ofchloroform and 4 gm (0.02 mol) MCPBA in 100 ml of chloroform.

The crude material is recrystallized from ethanol to yield 5.5 gm (90%theory) of pure product.

Melting point 138°-141° C.

IR Bands NO 1240, 838 CM⁻¹, SO 1050 cm⁻¹.

Compound 138

2-(2,3,6-Trimethylphenylmethylsulfonyl)pyridine N-oxide

The procedure employed is identical to that of Example 139 using 10.4 gm(0.04 mol) 2-(2,3,6-trimethylphenylmethylthio)pyridine N-oxide in 50 mlof chloroform and 16 gm (0.08 mol) MCPBA in 200 ml of chloroform.

The oily residue from the work-up crystallizes and is recrystallizedfrom ethanol to give 7.9 gm (69% theory) of pure product.

Melting point 152°-155° C.

Analysis based on C₁₅ H₁₇ NO₃ S--Calc: C 61.83; H 5.88; N 4.81. Found: C61.28; H 5.87; N 4.92.

Compound 63

2-(3-Methylphenylmethylsulfinyl)pyridine N-oxide

The procedure employed is identical with that of Example 68 using 4.6 gm(0.02 mol) 2-(3-Methylphenylmethylthio)pyridine N-oxide in 50 ml ofchloroform and 4 gm (0.02 mol) MCPBA in 100 ml chloroform.

Crude material is recrystallized from ethylacetate to give 2 gm (45%theory) of pure product.

Melting point 67°-71° C.

Analysis based on C₁₃ H₁₃ NO₂ S--Calc: C 63.20; H 5.26; N 5.66. Found: C63.14; H 5.71; N 5.73.

Compound 60

2-(4-Methoxyphenylmethylsulfinyl)pyridine N-oxide

The procedure employed is identical to that of Example 68 using 7 gm(0.028 mol) 2-(4-methoxyphenylmethylthio)pyridine N-oxide in 50 ml ofchloroform and 5.6 gm (0.028 mol) MCPBA in 100 ml chloroform.

The crude material is recrystallized from ethanol to give 6 gm (82%theory) of pure product.

Melting point 140°-143° C.

IR Bands NO 1250, 835 cm⁻¹, SO 1040.

Compound 121

2-(3,4-dichlorophenylmethylsulfinyl)pyridine N-oxide

The procedure employed is identical to that of Example 68 using 8 gm(0.028 mol) 2-(3,4-dichlorophenylmethylthio)pyridine N-oxide in 50 ml ofchloroform and 5.6 gm (0.028 mol) MCPBA in 100 ml chloroform.

The crude material is recrystallized from ethanol to give 5.6 gm (82%theory) of pure product.

Melting point 133°-135° C.

Analysis based on C₁₂ H₉ Cl₂ NO₂ S--Calc: C 47.70; H 3.00; N 4.64.Found: C 47.44; H 2.92; N 4.71.

Compound 58

2-(2-Phenylethylsulfinyl)pyridine N-oxide

The procedure employed is identical to that of Example 68 using 2.8 gm(0.012 mol) 2-(2-phenylethylthio)pyridine N-oxide in 25 ml of chloroformwith 2.4 gm (0.012 mol) MCPBA in 50 ml chloroform.

The product is an oil and purity is determined by TLC. Structure isverified by IR.

Significant Bands NO 1250, 845 cm⁻¹, SO 1050 cm⁻¹, 5 ArCH 750, 695 cm⁻¹.

Compound 122

2-(1-[2,5-Dimethylphenyl]dodecylthio)pyridine N-oxide

A mixture of 46.2 gm (0.15 mol) of 1-phenyldodecylchloride, 54 gms of a40% aqueous solution of the sodium salt of 2-mercaptopyridine N-oxide(0.15 mol) and 100 ml of ethanol was warmed to 60° with stirring for aperiod of 2 hours. The cooled reaction mixture was poured into 600 mlwater with agitation. The precipitated solid was filtered, washed withwater and dried. Recrystallization from ethyl acetate yielded 30 gms(50% theory) of white crystalline product.

Melting point 90°-92° C.

Analysis based on C₂₅ H₃₇ NOS--Calc: C 75.15; H 9.33; N 3.51. Found: C75.19; H 9.45; N 3.56.

Surprisingly the 2-thio, 2-sulfinyl and 2-sulfonyl pyridine N-oxidesdisclosed herein have novel and variable plant regulating properties.Through coordination of the proper mode of application, dosage andtiming the compounds of this series give such varying responses asgrowth stimulation, growth retardation and increased productivity.

Particularly interesting retardant and stimulation responses to theapplication of these compounds include the following areas:

Turf

The maintenance of grasses normally employed for functional and estheticpurposes about homes, factories and highways includes regular mowing.For highway and commercial upkeep and the service represents aconsiderable cost factor and to the homeowner a necessary nuisance; attimes the turf may turn brown temporarily and unwanted root retardationresults. To date turf control has been attained to a certain degree withmaleic hydrazide but pronounced browning of the tops and unwanted rootretardation result. The compounds employed in this invention show uniqueproperties in that the turf top growth is retarded without losing thedesirable greenness, and root growth in many cases actually showsenhancement yielding a healthier sod.

The turf species of interest include Manhattan rye grass, Jamestownchewings fescue, Colonial bent, Kingston bent, Bermuda, Baron bluegrassand St. Augustine.

Preferred pyridine N-oxide derivatives which can be employed as turfretardants in accordance with the invention include:

    ______________________________________                                        No.                                                                           ______________________________________                                        109*   2-(1-[2,5-dimethylphenyl]ethylsulfonyl)pyri-                                  dine N-oxide                                                            35*   2-(1-phenylethylsulfonyl)pyridine N-oxide                              105    2-(1-[4-methylphenyl]ethylsulfonyl)pyridine                                   N-oxide                                                                 42    2-(2,6-dichlorophenylmethylsulfinyl)pyridine                                  N-oxide                                                                 139** 2-(1-[2,4,6-trimethylphenyl]ethylsulfonyl)-                                   pyridine N-oxide                                                        31    2-(2,4,6-trimethylphenylmethylsulfonyl)pyri-                                  dine N-oxide                                                            79    2-(1-[4-chlorophenyl]ethylsulfonyl)pyridine                                   N-oxide                                                                 14    2-(2,5-dimethylphenylmethylsulfonyl)pyridine                                  N-oxide                                                                 57    2-(2,4-dichlorophenylmethylsulfinyl)pyridine                                  N-oxide                                                                138    2-(2,3,6-trimethylphenylmethylsulfonyl)pyri-                                  dine N-oxide                                                            6     2-(3,4-dimethylphenylmethylsulfonyl)pyridine                                  N-oxide                                                                 68**  2-(2-methylphenylmethylsulfinyl)pyridine N-                                   oxide                                                                   27    2-(2-methylphenylmethylsulfonyl)pyridine N-                                   oxide                                                                  142    2-(2,3,6-trimethylphenylmethylsulfinyl)pyri-                                  dine N-oxide                                                           128    2-(2-oxo-[2,5-dimethylphenyl]ethylsulfinyl)-                                  pyridine N-oxide                                                       ______________________________________                                          *most preferred                                                              **root stimulant -- top retardant                                        

The turf retardants described herein are highly active on the variety ofturf grasses when applied in dosages of 0.125 to 8 pounds per acre. Thecompounds may be formulated as liquid or impregnated granule for easyapplication or in any of a number of other forms as known to the art.The formulations may contain more than one of the described pyridineN-oxide derivatives, other active retardants or synergists.

Cereal Grains

The dual response to retardation and stimulation is of value on cerealgrains (particularly wheat, as well as barley, rye, oats, rice, etc.) toproduce a shorter plant with a larger number of seed heads per plant bypromoting increased tillering. The overall results are to reducepossibility for lodging with increased productivity.

Preferred 2-pyridine N-oxide derivatives which can be employed as plantregulators on wheat or other cereal grains in accordance with theinvention include:

    ______________________________________                                        No.                                                                           ______________________________________                                         14    2-(2,5-dimethylphenylmethylsulfonyl)pyridine                                  N-oxide                                                                 6     2-(3,4-dimethylphenylmethylsulfonyl)pyridine                                  N-oxide                                                                109    2-(1-[2,5-dimethylphenyl]ethylsulfonyl)pyridine                               N-oxide                                                                ______________________________________                                    

Sugar Producing Species

Increase in productivity of sugar producing species, such as sugar beetsand sugar cane, is a valuable aspect of the invention. Thus, forexample, it has been demonstrated that treatment of sugar beets with theclaimed compounds results in increased beet weight. To exemplify this,sugar beets were planted in the field at Bethany, Connecticut.2-(2,6-Dichlorophenylmethylsulfinyl)pyridine N-oxide (Compound 42) wasapplied as a soil treatment at 4 and 8 pounds per acre at the end ofJuly when the beets were about half grown. About 1 month later theeffect of the treatment on photorespiration was determined by enclosinga large leaf of a plant in a plastic chamber, impermeable to CO₂. Airwas aspirated from the chamber at intervals and the CO₂ level determinedby infra red absorption of the gas. At equilibrium the beets treatedwith the compound at 4 pounds per acre reduced the CO₂ level by 35% whencompared to the untreated control exposed to the same conditions. TheCO₂ level at 8 pounds per acre was reduced by 36% when compared to thecontrol. At harvest there was a yield increase of 8 and 12% at 4 and 8pounds per acre respectively, when compared to the controls.

Preferred 2-pyridine N-oxides employed as a beet root stimulant inaccordance with the invention include:

    ______________________________________                                        No.                                                                           ______________________________________                                        42*   2-(2,6-dichlorophenylmethylsulfinyl)pyridine                                  N-oxide                                                                  68   2-(2-methylphenylmethylsulfinyl)pyridine N-oxide                        131   2-(2-oxo-2-[2,5-diisopropylphenyl]ethylsulfinyl)-                             pyridine N-oxide                                                        140   2-(2-nitrophenylmethylsulfonyl)pyridine N-oxide                          115* 2-(1-[2,5-dimethylphenyl]octylthio)pyridine                                   N-oxide                                                                 122   2-(1-[2,5-dimethylphenyl]dodecylthio)pyridine                                 N-oxide                                                                 ______________________________________                                         *most preferred                                                          

Legumes

The employment of the compounds of this invention on soybeans and otherlegumes such as beans, peanuts, alfalfa and clover, makes it possible toincrease the efficiency of the plant and thereby vastly increaseproductivity. This is accomplished without altering the normal growthsignificantly. To exemplify this the Corsoy variety of soybeans wasplanted in the field at Bethany, Connecticut. When the plants hadcompleted setting of pods, 2-(1-phenylethylsulfonyl)-pyridine N-oxide(Compound 35) was sprayed at 2000 parts per million to wet the foliage.About one month later one of the plants in the treated plot was enclosedin a plastic which is not permeable to CO₂. Air was aspirated from theplastic chamber at intervals and the CO₂ level determined by infra redabsorption of the gas. At equilibrium the CO₂ level was reduced by 45%when compared to an untreated control plant. This reduction inphotorespiration was accompanied by an increase in yield of theharvested soybeans by 6.0%.

Preferred 2-pyridine N-oxides which can thus be employed as productivityenhancers in accordance with the invention include:

    ______________________________________                                        No.                                                                           35*   2-(1-phenylethylsulfonyl)pyridine N-oxide                               42*   2-(2,6-dichlorophenylmethylsulfinyl)pyridine                                  N-oxide                                                                 75    2-(2-fluorophenylmethylsulfinyl)pyridine N-oxide                        68    2-(2-methylphenylmethylsulfinyl)pyridine N-oxide                        27    2-(2-methylphenylmethylsulfonyl)pyridine N-oxide                        96    2-(4-cyanophenylmethylsulfinyl)pyridine N-oxide                         57*   2-(2,4-dichlorophenylmethylsulfinyl)pyridine                                  N-oxide                                                                 83*   2-(2,3,6-trichlorophenylmethylthio)pyridine                                   N-oxide                                                                 50*   2-(2,5-dimethylphenylmethylsulfinyl)pyridine                                  N-oxide                                                                 67    2-(3,4-dimethylphenylmethylsulfinyl)pyridine                                  N-oxide                                                                 79    2-(1-[4-chlorophenylethylsulfonyl)pyridine                                    N-oxide                                                                 114   2-(1-[2-naphthyl]ethylsulfonyl)pyridine N-oxide                         128   2-(2-oxo-2-[2,5-dimethylphenyl]ethylsulfinyl)-                                pyridine N-oxide                                                         2    2-(phenylmethylthio)pyridine N-oxide                                    ______________________________________                                         *most preferred                                                          

Cotton

In order to facilitate mechanical harvesting it is desirable to reducethe height of the cotton plant to decrease the possibility of lodging.The action of the compounds of this invention, when employed as a foliarspray, terminates apical growth. This termination of growth, once thedesired number of bolls has formed, prevents the formation and settingof additional bolls which never mature resulting in lower crop yields.

Field test have shown that 2-(2,6-dichlorophenylmethylsulfinyl)pyridineN-oxide (Compound 42), for example, terminates growth of cotton,promotes maturity of the bolls for earlier harvest and causes youngsquares to abscise. These are the preferred feeding sites of the bollweevil and pink bollworm, hence their elimination reduces thedesirability of this plant for these insects.

High rates promoted abscission of the leaves and prevented regrowth ofthe axillary buds. This response is desirable for mechanical harvestingof the mature cotton.

Productivity of plants or the production of dry weight per unit ofground area is primarily determined by the total CO₂ assimilated duringphotosynthesis, minus the CO₂ released as photorespiration. Theinvention makes it possible to markedly reduce photorespiration, henceimprove productivity of plants. Productivity by the following plants canbe improved: vegetables such as lettuce, beans, spinach; cereals such aswheat, oats, barley, rice; tobacco, hay grasses, sugar beets, cotton andsunflower.

Promotion of inhibition of axillary buds growth can be useful forcontrol of suckers on tabacco, prevention of sprouting of root cropssuch as potatoes, beets and carrots.

The promotion of abscission can be useful as a harvest aid for cotton,the mechanical harvesting of fruits such as citrus and cherries.

The promotion of tillering and reduction of height of grain can beuseful in prevention of lodging and increasing yield of oats, barley,rye and rice.

The promotion of root growth can increase yields of such undergroundroot crops as beets, carrots and potatoes.

Preferred pyridine N-oxide derivatives which can thus be employed asgrowth terminators in accordance with the invention include:

    ______________________________________                                        No.                                                                           61     2-(phenylmethylsulfinyl)pyridine N-oxide                               63     2-(3-methylphenylmethylsulfinyl)pyridine                                      N-oxide                                                                10     2-(4-chlorophenylmethylthio)pyridine N-oxide                           60     2-(4-methoxyphenylmethylsulfinyl)pyridine                                     N-oxide                                                                42*    2-(2,6-dichlorophenylmethylsulfinyl)pyridine                                  N-oxide                                                                121    2-(3,4-dichlorophenylmethylsulfinyl)pyridine                                  N-oxide                                                                109    2-(1-[2,5-dimethylphenyl]ethylsulfonyl)pyri-                                  dine N-oxide                                                           83     2-(2,3,6-trichlorophenylmethylthio)pyridine                                   N-oxide                                                                58     2-(2-phenylethylsulfinyl)pyridine N-oxide                              ______________________________________                                         *most preferred                                                          

Formulations of the compounds for use in this invention can be preparedin conventional ways. They include dusts, granules, pellets, solutions,suspensions, emulsions, wettable powders, emulsifiable concentrates, oilsuspensions, dispersions to include flowable formulations, for examplethe active ingredient suspended either in oil or water. Formulationsalso include slow release compositions as a part of any of the followingprocedures and also include encapsulation of the active ingredient. Manyof these may be applied directly to the seed, soil or to the plants.Sprayable formulations can be extended in suitable media and used atspray volumes of from a few pints to several hundred gallons per acre.High strength concentrates are primarily used as intermediates forfurther formulation. The formulations, broadly, contain about 0.5 to 99%by weight of active ingredient(s) and at least one of (a) about 0.1 to50% surfactant(s) and (b) about 0.5 to 99% solid or liquid diluent(s).More specifically, they will contain these ingredients in the followingapproximate proportions:

    ______________________________________                                        Percent by Weight                                                                          Active            Surfac-                                                     Ingredient                                                                            Diluent(s)                                                                              tant(s)                                        ______________________________________                                        Wettable Powders                                                                             20-90      0-89      1-10                                      Oil Suspensions,                                                              Emulsions, Solutions                                                          (including Emulsifi-                                                          able concentrates)                                                                            5-50     40-95      0-50                                      Aqueous Suspensions                                                                          10-50     40-90      1-50                                      Dusts           1-25     70-99     0-5                                        Granules and Pellets                                                                          1-95      5-99      0-15                                      High Strength Con-                                                            centrates       90-100    0-10     0-5                                        ______________________________________                                    

Lower or higher levels of active ingredient can, of course, be presentdepending on the intended use and the physical properties of thecompound. Higher ratios of surfactant to active ingredient are sometimesdesirable, and are achieved by incorporation into the formulation or bytank mixing. Lower concentrations of active ingredient can aid inaccurate application at the very low rates reached for this invention.Sprayable and dust formulations are preferred.

Typical solid diluents are described in Watkins, et al., "Handbook ofInsecticide Dust Diluents and Carriers", 2nd Ed., Dorland Books,Caldwell, N. J. The more absorptive diluents are preferred for wettablepowders and the denser ones for dusts. Typical liquid diluents andsolvents are described in Marsden, "Solvents Guide", second edition,Interscience, New York, 1950. Solubility under 0.5% is preferred forsuspension concentrates; solution concentrates are preferably stableagainst phase separation at 0° C. "McCutcheon's Detergents andEmulsifiers Annual", Allured Publ. Corp., Ridgewood, New Jersey, as wellas Sisely and Wood, "Encyclopedia of Surface Active Agents", ChemicalPubl. Co. Inc., New York, 1964, list surfactants and recommended uses.All formulations can contain minor amount of additives to reduce foam,caking, corrosion, microbiological growth, etc.

The methods of making such formulations are well known. Solutions areprepared by simply mixing the ingredients. Fine solid compositions aremade by blending and, usually, grinding as in a hammer or fluid energymill. Suspensions are prepared by wet milling (see, for example,Littler, U.S. Pat. No. 3,060,084) or by blending liquids, inertingredients and previously ground dry active ingredients, followed by adispersion cycle. Granules and pellets may be made by spraying theactive material upon preformed granular carriers or by agglomerationtechniques. See J. E. Browning, "Agglomeration", Chemical Engineering,December 4, 1967, pp. 147 ff. and "Perry's Chemical Engineer'sHandbook", 4th Ed., McGraw-Hill, N. Y., 1963, pp. 8-59 ff.

For further information regarding the art of formulation, see forexample:

H. M. Loux, U.S. Pat. No. 3,235,361, Feb. 15, 1966, Col. 6, Line 16through Col. 7, Line 19 and Examples 10 through 41.

R. W. Luckenbaugh, U.S. Pat. No. 3,309,192, Mar. 14, 1967, Col. 5, Line43 through Col. 7, line 62 and Ex. 8, 12, 15, 39, 41, 52, 53, 58, 132,138-140, 162-164, 166, 167, 169-182.

H. Gysin and E. Knusli, U.S. Pat. No. 2,891,855, June 23, 1959, Col, 3,Line 66 through Col. 5, Line 17 and Examples 1-4.

G. C. Klingmah, "Weed Control as a Science", John Wiley and Sons, Inc.,New York, 1961 pp. 81-96.

J. D. Fryer and S. A. Evans, "Weed Control Handbook", fifth editionBlackwell Scientific Publications, Oxford, 1968, pp. 101-103.

Typical formulations are shown in the following examples. Allpercentages are by weight.

Formulation A

    ______________________________________                                        Formulation A                                                                 Wettable Powder       Percent                                                 ______________________________________                                        Compound 16           40                                                      dioctyl sodium sulfosuccinate                                                                       1.5                                                     sodium ligninsulfonate                                                                              3                                                       low viscosity methyl cellulose                                                                      1.5                                                     attapulgite clay      54                                                      ______________________________________                                    

Thoroughly blend the ingredients then pass through an air mill toproduce an average particle size under 15 microns. Reblend and siftthrough a U.S.S. No. 50 sieve (0.3 mm opening) before packaging.

All compounds of the invention may be formulated in the same manner.

Formulation B

    ______________________________________                                        Formulation B                                                                 High Strength Concentrate                                                                           Percent                                                 ______________________________________                                        Compound 42           98.5                                                    silica aerogel        0.5                                                     synthetic amorphous fine silica                                                                     1.0                                                     ______________________________________                                    

Blend and grind the ingredients in a hammer mill to produce a highstrength concentrate essentially all passing a U.S.S. sieve (0.3 mmopenings). This material may then be formulated in a variety of ways.

Formulation C

    ______________________________________                                        Formulation C                                                                 Dust                Percent                                                   ______________________________________                                        high strength concentrate                                                     formulation B       25.4                                                      pyrophyilite powdered                                                                             74.6                                                      ______________________________________                                    

Thoroughly blend the ingredients and package for use.

Formulation D

    ______________________________________                                        Formulation D                                                                 Aqueous Suspension    Percent                                                 ______________________________________                                        Compound 139          25                                                      hydrated attapulgite clay                                                                           3                                                       crude calcium ligninsulfonate                                                                       10                                                      sodium dihdrogen phosphate                                                                          0.5                                                     water                 61.5                                                    ______________________________________                                    

Grind the ingredients together in a sand mill until the solid particleshave been reduced to diameters under 10 microns.

Formulation E

    ______________________________________                                        Formulation E                                                                 Oil Suspension          Percent                                               ______________________________________                                        Compound 184            25                                                    polyoxyethylene sorbitol hexaoleate                                                                    5                                                    highly aliphatic hydrocarbon oil                                                                      70                                                    ______________________________________                                    

Grind the ingredients together in a sand mill until the solid particleshave been reduced to under about 5 microns. The resulting thicksuspension may be applied directly, but preferably after being extendedwith oils or emulsified in water.

Illustrative plant regulant responses for typical 2-thio, 2-sulfinyl and2-sulfonyl pyridine N-oxides of the formula stated above are shown inTable II, where plant regulant responses are indicated by the symbolsdefined at the beginning of Table II.

                                      TABLE II                                    __________________________________________________________________________                    Plant Regulators                                              __________________________________________________________________________            RW  = retards wheat >30% 6000 ppm                                             RT  = retards turf >50%/8.5#/A                                                RC  = retards cotton >30%                                                     RS  = retards soybeans >30%                                                   STR = stimulates turf roots >25%                                              SSB = stimulates sugar beets >25%                                             WT  = wheat tillering                                                         P   = enhances production of soybeans >50%                            __________________________________________________________________________     ##STR211##                                                                   No.   n R.sub.1  R.sub.2       Activity                                       __________________________________________________________________________    1     1 H       2,2-dichlorocyclo-                                                                           RT, RC                                                         propyl                                                        2     0 H       phenyl         P, RC                                          3     2 H       1-methyl-2,2-dichloro-                                                                       RC                                                             cyclopropyl                                                   4     2 H       phenyl         RT                                             5     0 H       1-naphthyl     RT                                             6     2 H       3,4-dimethylphenyl                                                                           RT, WT                                         7     2 H       4-methylphenyl RT                                             8     2 H       4-chlorophenyl RT                                             9     2 H       1-naphthyl     RT, RW                                         10    0 H       4-chlorophenyl RC                                             11    0 H       4-methylphenyl RC                                             12    1 H       4-chlorophenyl RT, RC                                         13    0 H       2,5-dimethylphenyl                                                                           RT                                             14    2 H       2,5-dimethylphenyl                                                                           RT, RW                                         15    2 H       4-nitrophenyl  RS                                             16    2 H       cyclohexyl     RS                                             17    2 H       2,2-dichlorocyclo-                                                                           RT                                                             propyl                                                        18    0 H       2-ethylphenyl  RT                                             19    1 H       methyl         RW                                             20    2 H       2-benzothiazole                                                                              RS                                             21    0 H       2-methylphenyl RT, RS                                         22    2 H       2-chlorophenyl RT                                             23    0 H       2-chlorophenyl RT                                             24    2 H       n-undecyl      RC                                             25    0 H       n-decyl        RS                                             26    0 CH.sub.3                                                                              phenyl         RS                                             27    2 H       2-methylphenyl STR, RT, P, RS                                 28    2 H       x, y-dichloro- RT                                                             phenyl                                                        29    0 H       2,6-dichlorophenyl                                                                           RT                                             30    0 H       2,4,6-trimethyl-                                                                             RT                                                             phenyl                                                        31    2 H       2,4,6-trimethylphenyl                                                                        RT, P, RW                                      32    2 H       2,6-dichlorophenyl                                                                           RT, RW                                         33    2 H       3-trifluoromethyl-                                                                           RW                                                             phenyl                                                        34    2 H       2,4-dichlorophenyl                                                                           RW                                             35    2 CH.sub.3                                                                              phenyl         STR, RT                                        36    0 H       2,4-dichlorophenyl                                                                           RT                                             37    2 H       2-methoxy-5-nitro-                                                                           RT                                                             phenyl                                                        38    0 H       3,4-dimethylphenyl                                                                           RT                                             39    2 H       isopropenyl    RT                                             40    0 H       benzyl         RT                                             41    2 H       benzyl         RT                                             42    1 H       2,6-dichlorophenyl                                                                           RT, RW, RS                                     43    0 H       2-fluorophenyl RT, RC, RW                                     44    2 H       2-chloro-3,4-dioxy-                                                                          P, RW                                                          methylene                                                     45    2 H       2-fluorophenyl RT, RW                                         46    2 ethyl   n-butyl        RT, RC                                         47    2 H       2-ethylphenyl  RT, RW                                         48    2 methyl  n-butyl        RT                                             49    2 cyclohexyl             RT                                             50    1 H       2,5-dimethylphenyl                                                                           RT, P, RW                                      51    0 methyl  methyl         RT                                             52    0 H       2-cyanophenyl  RS                                             53    2 cycloheptyl            RW                                             54    2 H       2-cyanophenyl  RT                                             55    2 methyl  methyl         RT                                             56    0 cycloheptyl            RT                                             57    1 H       2,4-dichlorophenyl                                                                           RT, P, RS, RW                                  58    1 H       benzyl         RC, RW, RS                                     59    1 H       3-trifluoromethyl-                                                                           RT, RC, RS                                                     phenyl                                                        60    1 H       4-methoxyphenyl                                                                              RT, RC                                         61    1 H       phenyl         RT, RS                                         62    0 H       3-methylphenyl RT, RS                                         63    1 H       3-methylphenyl RT, RC, RS                                     64    2 H       3-methylphenyl RT, P, RS, RW                                  65    1 H       2,4,6-trimethyl-                                                                             RT, P, RW, RS                                                  phenyl                                                        66    1 H       2-chlorophenyl RT, RS                                         67    1 H       3,4-dimethylphenyl                                                                           RT, P, RW, RS                                  68    1 H       2-methylphenyl STR, RT, SSB, RS                               69    1 H       2-cyanophenyl  STR, RT, RS, RW                                70    1 H       4-methylphenyl RT, RS                                         71    2 H       3-fluorophenyl RT, RC                                         72    1 H       4-fluorophenyl RT, RS, RW, RC                                 73    2 H       4-fluorophenyl RT, RC                                         74    1 H       3-fluorophenyl RT, RS, RW                                     75    1 H       2-fluorophenyl RT, P, RS                                      76    1 H       oxophenyl      RT, RW                                         77    2 H       oxophenyl      RS                                             78    0 methyl  4-chlorophenyl RS                                             79    2 methyl  4-chlorophenyl STR, RT, P, RS, RW                             80    0 propyl  phenyl         P, RC, RS                                      81    0 methyl  4-methylphenyl RC                                             82    0 H       pentachlorophenyl                                                                            RC                                             83    0 H       2,3,6-trichloro-                                                                             RT, P, RC, RW                                                  phenyl                                                        84    0 H       4-cyanophenyl  RT, P                                          85    0 H       oxo-4-(2,2-dichloro-                                                                         RT                                                             cyclopropyl)phenyl                                            86    0 H       oxo-2,4-dimethyl-                                                                            RT                                                             phenyl                                                        87    0 methyl  2-naphthyl     RT, RS                                         88    2 H       2-methoxy-5-methyl-                                                                          RT, RS, RW                                                     phenyl                                                        89    2 H       2-bromo-5-methoxy-                                                                           RT, RS, RW                                                     phenyl                                                        90    2 H       pentachlorophenyl                                                                            RS, RW                                         91    1 H       pentachlorophenyl                                                                            RT, RS, RW                                     92    2 H       2,3,6-trichloro-                                                                             RT, RS, RW                                                     phenyl                                                        94    1 H       2,3,6-trichloro-                                                                             RT                                                             phenyl                                                        95    2 H       4-cyanophenyl  RT, RW                                         96    1 H       4-cyanophenyl  RT, P                                          97    2 H       oxo-2,4-dimethyl-                                                                            RT, RW                                                         phenyl                                                        98    1 H       oxo-2,4-dimethyl-                                                                            RT, RW, RS                                                     phenyl                                                        99    0 methyl  2,5-dimethylphenyl                                                                           P, RW, RS                                      100   0 methyl  4-bromophenyl  RW                                             101   2 H       2,5-diisopropyl-                                                                             RW                                                             phenyl                                                        102   1 H       2,5-diisopropyl-                                                                             STR, RT, RW                                                    phenyl                                                        103   1 H       oxo-4-(2,2-dichloro-                                                                         RS                                                             cyclopropyl)phenyl                                            104   2 propyl  phenyl         RS, RW                                         105   2 methyl  4-methylphenyl RT, RS, RC, RS                                 106   2 methyl  4-methylphenyl RT                                             107   2 methyl  2-thienyl      RW, RS                                         108   2 methyl  4-fluorophenyl RT, RW, RS, RC                                 109   2 methyl  2,5-dimethylphenyl                                                                           RT, RC, RW, RS, WT                             110   0 ethyl   phenyl         RS, RW                                         111   0 methyl  3,4-dichlorohenyl                                                                            RC                                             112   0 H       3,4-dioxymethylene-                                                                          RC                                                             phenyl                                                        113   1 methyl  4-fluorophenyl RC, RS, RW                                     114   2 methyl  2-naphthyl     STR, RT, P                                     115   0 n-heptyl                                                                              2,5-dimethylphenyl                                                                           STR, RT, SSB                                   116   1 methyl  4-bromophenyl  RS, RC                                         117   2 methyl  4-bromophenyl  RW, RS, RC                                     118   2 ethyl   phenyl         RC, RS                                         119   0 H       oxo-2,5-dimethyl-                                                                            P                                                              phenyl                                                        120   1 H       oxo-4-fluorophenyl                                                                           RW, RC                                         121   1 H       3,4-dichlorophenyl                                                                           RC, RS, RW                                     122   0 n-undecyl                                                                             2,5-dimethylphenyl                                                                           SSB, RW                                        123   0 H       3-bromophenyl  P, RC, RW                                      124   2 H       3-bromophenyl  STR, RT                                        125   1 H       3-bromophenyl  STR, RT, RC, RW, RS                            126   2 methyl  3,4-dichlorophenyl                                                                           STR, RT                                        127   2 H       oxo-2,5-dimethyl-                                                                            RT, RC, RW                                                     phenyl                                                        128   1 H       oxo-2,5-dimethyl-                                                                            RT, P, RC, RS, RW                                              phenyl                                                        129   1 H       3,4-dioxymethylene-                                                                          RT, RC, RS, RW                                                 phenyl                                                        130   2 H       3,4-dioxymethylene-                                                                          STR, RT, RC, RS, RW                                            phenyl                                                        131   1 H       oxo-2,5-diosopropyl-                                                                         STR, RT, SSB, RC                                               phenyl                                                        132   2 H       2-propionic acid                                                                             RC                                             133   1 methyl  oxo-phenyl     RC, RS, RW                                     134   2 methyl  oxo-phenyl     RW                                             135   0 H       2,3,6-trimethyl-                                                                             RS                                                             phenyl                                                        136   0 H       2-nitrophenyl  RC, RW                                         137   0 H       4-(2,2-dichloro-                                                                             RW                                                             cyclopropyl)phenyl                                            138   2 H       2,3,6-trimethyl-                                                                             STR, RT, RS, RW                                                phenyl                                                        139   2 methyl  2,4,6-trimethyl-                                                                             RT                                                             phenyl                                                        140   2 H       2-nitrophenyl  STR, RT, SSB                                   141   1 H       2-nitrophenyl  STR, RT, RW, RS                                142   1 H       2,3,6-trimethyl-                                                                             RT, RW                                                         phenyl                                                        143   2 H       2-methyl(1-naphthyl)                                                                         RW                                             144   1 H       2-methyl-(1-naphthyl)                                                                        RT                                             145   1 phenyl  2-methylphenyl RW                                             146   2 H       1-iodophenyl   RS, RW                                         147   1 H       1-iodophenyl   RT, RW, RS                                     148   2 methyl  4-nitrophenyl  RT, RW                                         149   2 H       4(2,2-dichloro-                                                                              RT                                                             cyclopropyl)phenyl                                            150   1 H       4(2,2-dichloro-                                                                              RT, RS                                                         cyclopropyl)phenyl                                            151   2 methyl  1-naphthyl     RT, RW                                         152   1 methyl  1-naphthyl     RW                                             153   0 H       3,4-dimethoxyphenyl                                                                          RT, RW                                         154   1 H       3,4-dimethoxyphenyl                                                                          RW, RS                                         155   2 H       3,4-dmethoxyphenyl                                                                           RW, RS                                         156   2 methyl  2,5-diethylphenyl                                                                            RW, RW                                         157   0 methyl  2,5-diisopropyl-                                                                             RS                                                             phenyl                                                        158   1 cyclopentyl            RT                                             159   2 cyclopentyl            RT                                             160   2 H       2,5-dimethoxyphenyl                                                                          RT, RS, RW                                     161   1 H       2,5-dimethoxyphenyl                                                                          RS, RW                                         162   1 H       2-ethoxyphenyl RS                                             163   2 H       2-ethoxyphenyl RW, RS                                         164   0 methyl  2-chloro-4-methyl-                                                            phenyl         RS                                             165   2 methyl  2-chloro-4-methyl-                                                                           RS, RW                                                         phenyl                                                        166   1 methyl  2-chloro-4-methyl-                                                                           RS, RW                                                         phenyl                                                        167   0 methyl  2-chloro-5-methyl-                                                                           RT                                                             phenyl                                                        168   2 methyl  2,5-diisopropyl-                                                                             RT                                                             phenyl                                                        169   0 H       2,3,5,6-tetrachloro-                                                                         RT                                                             4-methylphenyl                                                170   1 H       2,3,5,6-tetrachloro-                                                                         RT, RS, RW                                                     4-methylphenyl                                                171   2 H       2,3,5,6-tetrachloro-                                                                         RT                                                             4-methylphenyl                                                172   0 methyl  2,5-dichlorophenyl                                                                           RT                                             173   1 methyl  2-chloro-5-methyl-                                                                           RS, RW                                                         phenyl                                                        174   2 methyl  2-chloro-5-methyl-                                                                           RS, RW                                                         phenyl                                                        175   1 methyl  2,5-dichlorophenyl                                                                           RT, RW                                         176   2 methyl  2,5-dichlorophenyl                                                                           RT, RW, RS                                     177   1 methyl  2,4,5-trimethyl-                                                                             RW, RT                                                         phenyl                                                        178   2 methyl  2,4,5-trimethyl-                                                                             RS, RW, RT                                                     phenyl                                                        179   1 methyl  2,3,4-trimethyl-                                                                             RC, RW, RT                                                     phenyl                                                        180   2 methyl  2,3,4-trimethyl-                                                                             RC, RW, RT                                                     phenyl                                                        181   1 methyl  2,3,4,5-tetramethyl-                                                                         RT                                                             phenyl                                                        182   2 methyl  2,3,4,5-tetramethyl-                                                                         RC, RW, RS, RT                                                 phenyl                                                        183   1 H       3,4,5-trimethoxy-                                                                            RC, RS                                                         phenyl                                                        184   2 H       3,4,5-trimethoxy-                                                                            RT                                                             phenyl                                                        185   1 H       9-anthryl      RT                                             186   0 H       2-thienyl      RC                                             187   1 H       2-thienyl      RS, RW                                         188   2 H       2-thienyl      RC, RS, RW                                     189   1 methyl  phenyl         RT, RW                                         190   1 methyl  2,5-dimethylphenyl                                                                           RT, RC, RW                                     191   1 methyl  4-chlorophenyl RT, RC, RW                                     192   2 methyl  2,4-dichloro-3-                                                                              RC, RW                                                         methylphenyl                                                  193   1 methyl  2,4-dichloro-3-                                                                              RW                                                             methylphenyl                                                  194   0 methyl  benzyl         RC                                             195   2 isobutyl                                                                              2,5-dimethylphenyl                                                                           RT                                             196   2 methyl  benzyl         RT                                             197   1 methyl  benzyl         RT                                             198   0 methyl  2,5-dichlorothienyl                                                                          RT                                             199   0 benzyl  2,5-dimethylphenyl                                                                           RC                                             200   0 H       4-vinylphenyl  RW                                             201   1 H       4-vinylphenyl  RW, RS                                         202   0 methyl  4-biphenyl     RW                                             203   0 methyl  4-phenoxyphenyl                                                                              RW                                             204   2 methyl  4-phenoxyphenyl                                                                              RC                                             205   0 methyl  2-methyl-5-iso-                                                                              RC                                                             propylphenyl                                                  206   2 methyl  2-methyl-5-iso-                                                                              RC, RW                                                         propylphenyl                                                  207   0 methyl  5-indanyl      RC, RW                                         208   2 methyl  5-indanyl      RC                                             __________________________________________________________________________

preferred compounds employed in the method of the invention are those offormula I above wherein

n is 0, 1 or 2

R₁ is hydrogen, methyl or n-heptyl

R₂ is phenyl or phenyl substituted with from 1 to 3 substituents whichmay be the same or different and are selected from the group consistingof methyl and chlorine.

Particularly preferred are the following:

Compound 35, 2-(1-phenylethylsulfonyl)pyridine N-oxide, especially foruse on turf and legumes such as soybeans.

Compound 109, 2-[1-(2,5-dimethylphenyl)ethylsulfonyl]pyridine N-oxide,especially for use on turf.

Compound 42, 2-(2,6-dichlorophenylmethylsulfinyl)- pyridine N-oxide,especially for use on legumes such as soybeans, cotton, peanuts, andsugar-producing species such as sugar beets.

Compound 50, 2-(2,5-dimethylphenylmethylsulfinyl)- pyridine N-oxide,especially for use on legumes such as soybeans.

Compound 57, 2-(2,4-dichlorophenylmethylsulfinyl)- pyridine N-oxide,especially for use on legumes such as soybeans.

Compound 83, 2-(2,3,6-trichlorophenylmethylthio)- pyridine N-oxide,especially for use on legumes such as soybeans.

Compound 115, 2-(1-[2,5-dimethylphenyl]octylthio) pyridine N-oxide,especially for use on sugar-producing species such as sugar beets.

New compounds of formula II above that are particularly remarkable fortheir unusual activity are:

    ______________________________________                                        No.                                                                            80  2-(1-phenylbutylthio)pyridine N-oxide                                    115  2-(1-[2,5-dimethylphenyl)octylthio)pyridine N-oxide                      122  2-(1-[2,5-dimethylphenyl]dodecylthio)pyridine N-oxide                    ______________________________________                                    

The following examples will serve to illustrate the practice of theinvention in more detail.

EXAMPLE I Turf

The test solutions are prepared by dissolving 10 milligram samples inacetone followed by dilution to 100 ml with water and two drops of"Tween 20"(trademark; polyoxyethylene sorbitan monooleate). Thesolutions are equivalent to 8.5 pounds per acre/100 ml which could besubsequently diluted o 4.25 and 2.12 pounds per acre equivalents.

A. The turf grass species are grown in three inch styrofoam cups 6inches deep. The grass is planted and held in the cups until a good rootsystem develops to fill the cup. The test solution of the desiredconcentration is then poured on the soil surface as a drench. About 1week later the turf is clipped back to a uniform height. Percent growthinhibition is calculated by Abbotts formula compared to regrowth ofuntreated controls.

B. To observe root growth and top growth simultaneously a 3 inch blackplastic pipe 12 inches long was cut longitudinally to a length of 11inches to permit removal of a half section. A piece of copper screeningwas cemented to the bottom to confine the soil. The removable sectionwas secured with a plastic strap.

The experiments are carried out by removing a treated plug from itsstyrofoam cup and inserting it into the tube containing eight inches ofuntreated soil. The tubes are placed in racks at a 45° angle on agreenhouse bench with the removable section down to permit the roots togrow along its surface. The tops are clipped 1 week after treatment andregrowth is measured at the same time as root observations are made.

the following table illustrates the results obtained from typicalexperiments.

    __________________________________________________________________________    % TOP GROWTH INHIBITION   % ROOT GROWTH INHIBITION*                           Compound  St. Blue-                                                                             Ber-        St. Blue-                                                                             Ber-    Leaf                            No.   Rye Aug Fesc                                                                              muda                                                                              Ave.                                                                              Rye Aug Fesc                                                                              muda                                                                              Avg.                                                                              Color                           __________________________________________________________________________    109   93  100 100 100 98  0   0   -50 0   -13 Good                            139   73  100 100 75  87  0   0   +50 0   +13 Good                             35   87   78  79 100 86  0   0   -35 0    -9 Good                             79   93  100 100 25  80  -10 0   0   +25  +4 Good                             68   47   56  86 83  68  0   -50 0   -50 -25 Good                            Maleic                                                                        Hydrazide                                                                           80   67  75 79  75  100 100 100 100 100 Poor                            __________________________________________________________________________     Dosage 2.12 pounds/acre                                                       *- inhibition                                                                 +stimulated.                                                             

EXAMPLE II Cotton

The test solutions are prepared by dissolving 0.3 gm of compound in 10ml of acetone and diluting to 100 ml with water containing 0.3% "TritonX100"(trademark; isooctylphenyl polyethoxy ethanol). Dilution to 200 mlyields solutions of 1500 ppm.

Cotton plants are grown in 6 inch pots to a height of 12 inches.Replicated plants are then sprayed to the drip point at dosages of 3000and 1500 ppm. Height measurements are made two months after treatment.

The following table illustrates typical results obtained by thetreatments.

    ______________________________________                                        Compound                                                                              Dosage  % Height                                                      No.     ppm     Reduction                                                     ______________________________________                                        42      1500    50        2-(2,6-dichlorophenyl-                                                        methylsulfinyl)pyridine                                     3000    45        N-oxide                                             61      1500     7        2-(phenylmethylsulfinyl)                                    3000    27        pyridine N-oxide                                    121     1500    34        2-(3,4-dichlorophenyl-                                                        methylsulfinyl)pyridine                                     3000    36        N-oxide                                             58      1500    34        2-(phenylethylsulfinyl)                                     3000    32        pyridine N-oxide                                    10      1500    22        2-(4-chlorophenylmethyl-                                    3000    37        thio)pyridine N-oxide                               60      1500    44        2-(4-methoxyphenylmethyl-                                   3000    32        sulfinyl)pyridine N-oxide                           ______________________________________                                    

EXAMPLE III Soybeans

The test solutions are prepared by weighing out 0.3 gm of test compoundand dissolving in 10 ml of acetone. Dilution with water containing 125ppm of "Tween 20"to 800 ml gave a test solution of 375 ppm.

Corsoy variety of soybeans are grown in 6 inch pots containing 2 plantsper pot. When the plants are in the trifoliate stage replicates weresprayed to the drip point. Approximately 1 month later the number ofpods per plant are counted and compared with the controls.

The following table illustrates typical results obtained.

    ______________________________________                                        Compound     Average number                                                   No.          pods/plant      % Increase                                       ______________________________________                                        57           11.0            134                                              83           10.7            128                                              96           10.0            113                                              67            9.3             98                                              Untreated controls                                                                          4.7            --                                               Dosage at 375 pm                                                              ______________________________________                                    

EXAMPLE IV Wheat

The test solutions are made up by weighing out the compound anddissolving in 10 ml of acetone followed by dilution in water to giveequivalents of 4 to 6 pounds/acre.

Waldron wheat is grown in 6 inch pots with three plants per pot. Whenthe plant has reached the early boot stage the solution is poured intothe saucer. The soil completely absorbs the liquid by this treatment.After 3 months the mature wheat was measured and the number of heads perplant counted.

The following table illustrates results obtained from these tests.

    ______________________________________                                        Compound  Dosage    %           Avg. No. mature                               No.       lb/acre   Retardation heads/plant                                   ______________________________________                                         6        4         10          5.4                                                     6          9          6.7                                           14        4         51          4.3                                                     6         58          3.4                                           Untreated --        --          3.0                                           ______________________________________                                    

EXAMPLE V Sugarbeets

The test solutions are prepared by dissolving the weighed compound in 10ml of acetone followed by dilution to 100 ml with water containing 2drops of "Tween 20".

Sugarbeets are planted in 6 inch pots in the greenhouse at one per pot.When the tops become five inches tall and possess 16 leaves a soildrench is applied to replicates at rates of 1 to 2 pounds per acre.Approximately 3 months later the roots are freed from soil, weighed andcompared to controls.

The following table illustrates results obtained.

    ______________________________________                                                  Dosage      Avg. % increase in beet                                 Example   #/acre      root weight over controls                               ______________________________________                                         68       2           124                                                     140       2           105                                                     131       1           117                                                     115       1            76                                                     ______________________________________                                    

EXAMPLE VI Peanuts

The major production of peanuts in the United States is with runnertypes. Each branch from the main stem produces a flower at each node,starting at the main stem. The flower then produces a peg whichpenetrates the soil to form the peanut pod. This is a continuous processuntil harvest. Pods formed during the latter part of the summer do notmature by harvest time. It is desirable to reduce number of pods formedso that those already formed will mature to maximum size.

To demonstrate the ability of the present compounds to reduce podformation on runner type peanuts the following emulsifiable concentratewas prepared:

    ______________________________________                                        2-(2,6-dichlorophenylmethyl-                                                  sulfinyl) pyridine N-oxide                                                                          12 grams                                                emulsifying agent     10 grams                                                ethylene dichloride to                                                                             100 ml                                                                        122.39 grams.                                            ______________________________________                                    

The emulsifying agent was a nonionic-anionic blend of alkyl phenoxypolyethoxy ethanols and organic sulfonates (Emulsifier AH861[trademark],Rohm & Haas); the concentration of the invention compound was 1.0 poundper gallon.

Florigiant variety of Virginia type runner peanuts (Arachis hypogaea L.)were planted in deep flats, four plants per flat; 74 days later theywere sprayed to runoff with formulations made by diluting the aboveconcentrate to 1250 and 2500 ppm. Seven weeks later the plants wereharvested and the number of pods and pegs on each node were counted. Thefollowing table summarizes the data. It is apparent that the number ofpods and pegs were reduced by the treatment.

    ______________________________________                                        Total Number of Pods and Pegs                                                 on Four Peanut Plants                                                                Node Number                                                                   1   2     3     4   5   6   7   8   9   10  Total                      ______________________________________                                        Check pods   26    20  18  10  3   1   0   0   0   0                                                     78                                                                             pegs 5 13 9 7 11 8 7 2 7 1 70                                                            148                                                               Treat-                                                                        ment pods 15 22 11 1 1 3 0    53                                              1250                                                                          ppm pegs 4 4 1 1 0 3 2    15                                                              68                                                                Treat-                                                                        ment pods 22 14 5 1 0 2     44                                                2500                                                                          ppm pegs 4 5 8 1 1 0     19                                                               63                                     ______________________________________                                    

We claim:
 1. A method of regulating the natural growth or development ofplants which comprises applying to said plants an effectivenon-herbicidal plant-regulating amount of a 2-sulfinyl-, or2-sulfonyl-pyridine N-oxide compound of the formula ##STR212## wherein:n is 1 or 2;R₁ is hydrogen, C₁ to C₁₅ alkyl, phenyl or benzyl; R₂ ishydrogen, C₁ to C₁₂ alkyl, C₁ to C₄ alkenyl, C₂ or C₃ alkoxycarbonyl, C₅or C₆ alicyclic, phenyl provided R₁ is not phenyl, phenyl substitutedwith from 1 to 3 substituents which may be the same or different and areselected from the group consisting of C₁ to C₃ alkyl, halogen, cyano,nitro, C₁ or C₂ alkoxy, phenoxy, dioxymethylene and2,2-dichlorocyclopropyl; and phenyl substituted with 4 to 5 substituentswhich may be the same or different and are selected from methyl andchlorine; 1-methyl-2,2-dichlorocyclopropyl, 2,2-dichlorocyclopropyl,naphthyl, 9-anthryl, 5-indanyl, 4-biphenylyl, 2-benzothiazolyl,2-thienyl or benzyl; R₁ and R₂ may be joined together in the form of apolymethylene chain --(CH₂)_(m) -where m is 3,4 or 5 to form acarbocyclic ring; and when R₁ is hydrogen or methyl R₂ can be theradical ##STR213## where y is 0, 1 or 2 and the X's are the same ordifferent and are selected from C₁ to C₃ alkyl, halogen, and2,2-dichlorocyclopropyl.
 2. A method as in claim 1 in whichn is 1 or 2R₁ is hydrogen, methyl or n-heptyl R₂ is phenyl or phenyl substitutedwith 1 to 3 substituents which may be the same or different and areselected from the group consisting of methyl and chlorine.
 3. A methodas in claim 2 in which the said compound is applied to turf.
 4. A methodas in claim 2 in which the said compound is applied to soybeans.
 5. Amethod as in claim 2 in which the said compound is applied to cotton. 6.A method as in claim 2 in which the said compound is applied to sugarbeets.
 7. A method as in claim 2 in which the said compound is appliedto peanuts.
 8. A method as in claim 1 in which the said compound isapplied to turf, and the said compound is selected from the groupconsisting of2-(1-[2,5-dimethylphenyl]ethylsulfonyl) pyridine N-oxide2-(1-phenylethylsulfonyl)pyridine N-oxide2-(1-[4-methylphenyl]ethylsulfonyl)pyridine N-oxide2-(2,6-dichlorophenylmethylsulfinyl)pyridine N-oxide2-(1-[2,4,6-trimethylphenyl]ethylsulfonyl)-pyridine N-oxide2-(2,4,6-trimethylphenylmethylsulfonyl)pyridine N-oxide2-(1-[2-chlorophenyl]ethylsulfonyl)pyridine N-oxide2-(2,5-dimethylphenylmethylsulfonyl)pyridine N-oxide2-(2,4-dichlorophenylmethylsulfinyl)pyridine N-oxide2-(2,3,6-trimethylphenylmethylsulfonyl)pyridine N-oxide2-(3,4-dimethylphenylmethylsulfonyl)pyridine N-oxide2-(2-methylphenylmethylsulfinyl)pyridine N-oxide2-(2-methylphenylmethylsulfonyl)pyridine N-oxide2-(2,3,6-trimethylphenylmethylsulfinyl)pyridine N-oxide and2-(2-oxo-2-[2,5-dimethylphenyl]ethylsulfinyl)pyridine N-oxide.
 9. Amethod as in claim 8 in which the said compound is2-(1-phenylethylsulfonyl)pyridine N-oxide or2-(1-[2,5-dimethylphenyl]ethylsulfonyl)pyridine N-oxide.
 10. A method asin claim 1 in which the said compound is applied to wheat, and the saidcompound is selected from the group consistingof2-(2,5-dimethylphenylmethylsulfonyl)pyridine N-oxide2-(3,4-dimethylphenylmethylsulfonyl)pyridine N-oxide and2-(1-[2,5-dimethylphenyl]ethylsulfonyl)pyridine N-oxide.
 11. A method asin claim 1 in which the said compound is applied to sugar beets, and thesaid compound is selected from the group consistingof2-(2,6-dichlorophenylmethylsulfinyl)pyridine N-oxide2-(2-methylphenylmethylsulfinyl)pyridine N-oxide2-(2-oxo-2-[2,5-diisopropylphenyl]ethylsulfinyl)pyridine N-oxide.2-(2-nitrophenylmethylsulfonyl)pyridine N-oxide.
 12. A method as inclaim 11 in which the said compoundis2-(2,6-dichlorophenylmethylsulfinyl)pyridine N-oxide.
 13. A method asin claim 1 in which the said compound is applied to soybeans, and thesaid compound is selected from the group consistingof2-(1-phenylethylsulfonyl)pyridine N-oxide2-(2,6-dichlorophenylmethylsulfinyl)pyridine N-oxide2-(2-fluorophenylmethylsulfinyl)pyridine N-oxide2-(2-methylphenylmethylsulfinyl)pyridine N-oxide2-(2-methylphenylmethylsulfonyl)pyridine N-oxide2-(4-cyanophenylmethylsulfinyl)pyridine N-oxide2-(2,4-dichlorophenylmethylsulfinyl)pyridine N-oxide2-(2,5-dimethylphenylmethylsulfinyl)pyridine N-oxide2-(3,4-dimethylphenylmethylsulfinyl)pyridine N-oxide2-(1-[4-chlorophenyl]ethylsulfonyl)pyridine N-oxide2-(1-[2-naphthyl]ethylsulfonyl)pyridine N-oxideand2-(2-oxo-2-[2,5-dimethylphenyl]ethylsulfinyl)pyridine N-oxide.
 14. Amethod as in claim 13 in which the said compoundis2-(1-phenylethylsulfonyl)pyridine N-oxide2-(2,6-dichlorophenylmethylsulfinyl)pyridine N-oxide2-(2,4-dichlorophenylmethylsulfinyl)pyridine N-oxide2-(2,5-dimethylphenylmethylsulfinyl)pyridine N-oxide.
 15. A method as inclaim 1 in which the said compound is applied to cotton, and the saidcompound is selected from the group consistingof2-(phenylmethylsulfinyl)pyridine N-oxide2-(3-methylphenylmethylsulfinyl)pyridine N-oxide2-(4-methoxyphenylmethylsulfinyl)pyridine N-oxide2-(2,6-dichlorophenylmethylsulfinyl)pyridine N-oxide2-(3,4-dichlorophenylmethylsulfinyl)pyridine N-oxide2-(1-[2,5-dimethylphenyl]ethylsulfonyl)pyridine N-oxide2-(2-phenylethylsulfinyl)pyridine N-oxide.
 16. A method as in claim 15in which the said compoundis2-(2,6-dichlorophenylmethylsulfinyl)pyridine N-oxide.
 17. A method asin claim 1 in which the said compound is applied to peanuts and the saidcompound is2-(2,6-dichlorophenylmethylsulfinyl)pyridine N-oxide.
 18. Amethod as in claim 1 in which the said compoundis2-(1-phenylethylsulfonyl)pyridine N-oxide.
 19. A method as in claim 1in which the said compoundis2-[1-(2,5-dimethylphenyl)ethylsulfonyl]pyridine N-oxide.
 20. A methodas in claim 1 in which the said compoundis2-(2,6-dichlorophenylmethylsulfinyl)pyridine N-oxide.
 21. A method asin claim 1 in which the said compoundis2-(2,5-dimethylphenylmethylsulfinyl)pyridine N-oxide.
 22. A method asin claim 1 in which the said compoundis2-(2,4-dichlorophenylmethylsulfinyl)pyridine N-oxide.